Hydra runes other than venom have been buffed, and damage output of enemies has been nerfed again. See energy armor and hydra sections for details.
With all of the content nerfs, and class buffs, I consider Blizzard/Hydra to now be the "low gear" spec. It is amazing for a wizard without access to the millions of gold it takes to gear as a critical mass tank, an archon, or an arcane orb glass cannon. However, if you have access to great gear, it simply doesn't kill as fast as many other specs that have now become viable. If you are in that low gear situation, I recommend taking a look at my 300k Gold Budget Inferno Wizard Guide, in addition to this one.
Siegebreaker runs are now pointless, with the added yellow drops from elites. It is now much better to simply farm elites in whatever area you like. I've been doing pretty much all of act 3 to get the most mileage out of a 5 stack. The build below is still great for this, but I wouldn't recommend just doing siege, as you won't 5-stack very many elites that way.
There's a lot of talk about blizzard/hydra, it being perhaps the most popular spec for dealing with Acts 3 and 4 of Inferno, so it seems reasonable to have an introduction to the build (aimed at wizards trying it for the first time).
The philosophy of the spec is simple: you will kite everything. Given that, blizzard is a spammable snare (and does a little damage too), and thus an obvious choice. Hydra deals damage without you having to do anything, freeing you up to run screaming away from things, so it is another great choice. Venom hydra also simply has amazing damage per cast time compared to pretty much any other spell in existence for any class, so there's that, too.
The core of the build:
Blizzard with Snowbound: The damage on blizzard is pretty poor, but the snare effect is oh so good. Snowbound is really the only valid rune choice. As you kite monsters will constantly be moving out of your blizzards and need another blizzard to walk into, so you're going to need to be able to cast quite a few of them. Again think of this as a snare first, and a damage dealer second. You can kill packs of weak monsters with blizzard, but really the damage is quite bad.
Hydra with Venom Hydra: Our main damage dealer. Venom hydra is just ridiculously strong. The poison pools it casts stack up, and monsters walk through them and take damage. We're not talking about, in an ideal case, 5 pools of 18% damage each on top of each other, dealing 90% damage a tic (twice a second). Against a target who is standing still, venom hydra's DPS is truly amazing, considering that it isn't using up any of your casting time while doing it. We'l be dealing with less than ideal situations, but even then it is better than the other hydras.
Hydra with Arcane Hydra or Frost Hydra: Lightning and mammoth hydras are still not particularly good for us, but arcane hydra is great damage, and frost hydra can provide a very useful additional snare now that it has some range. Venom hydra still has the highest DPS if the target stands still, but when you're kiting multiple targets (they're moving off the venom pools), arcane hydra will do more damage.
Energy Armor with Force Armor: Every Inferno wizard has come to know and love force armor. It stops you getting one shot (assuming reasonable amounts of armor/resists/life). Thanks to this ability you are far tougher than the other ranged characters. You can go invulnerable with smoke screen, but you don't need to, because you can eat fireballs to the face. When that demon hunter runs out of discipline for spamming smoke screen you'll still have force armor preventing any arrows or spears or whatever is flying your way from one-shot-killing you.
Energy Armor with Prismatic Armor: Damage output of enemies was nerfed in 1.03, and again in 1.04. If you have enough effective health not to get wrecked by hits in the content you're doing, you should use prismatic armor instead of force.
Passives: Note that no passives are required as part of the core build. This gives you the freedom to choose passives to taste, rather than be forced into them like you are with, for example, arcane kiting, where you have to take temporal flux and astral presence.
A full build:
This is just one option, there are many, many variations using the three skills above, all of them called "blizzard/hydra," I will try to cover some of the options, but there are too many to go into all of them.
Magic Missile with Seeker: Any of the signature spells with long range and fast travel time is a valid choice for this build, but I like seekers the best. Seekers have high single target damage, which complements the otherwise area/untargeted damage you get from blizzard/hydra. Seekers can shoot around corners, kill targets off-screen, and most importantly, seekers let you be lazy. You can just sort of cast them in the general direction of bad guys, and they'll hit stuff. When you're whipping around to fire a shot or two while kiting, pinpoint targeting often goes by the wayside.
Teleport with Wormhole: Escape from vortex, get past waller walls, reverse kiting directions safely when you run out of room, or just quickly get distance on your enemies. Teleport is a kiter's dream spell. Some people use fracture, but since I also run with mirror image I prefer wormhole for the extra distance when changing kiting directions, or when the first teleport doesn't land me where I thought it would.
Mirror Image with Duplicates: Wow, what an amazing ability. Five clones of you pop out and take hits for you. Mirrors are great when you're fighting enemies with missile attacks like spear throwers or act 3 bats. Duplicates are also great for soaking hits from fallen while you try to pick off the shaman, or tanking blazing ghouls that ambushed you from behind. Duplicates breaks roots (jailer), slows (knockback), and even gets you out of being frozen. The only down side really is that it bumps you in a random direction when you cast it, and sometimes that direction could be towards an enemy or into a desecration, so plan accordingly.
Glass Cannon: More damage. Yay. Still won't get one-shot thanks to force armor.
Illusionist: Possibly the most amazing passive in existence, at least if you have both teleport and mirror image in your build. Between force armor and illusionist you have pretty amazing defense. Force armor stops you getting one shot, illusionist turns the hit that didn't kill you into instantly available defensive/escape abilities.
Galvanizing Ward: I always feel a little awkward about this one. The benefit is pretty much that I don't have to remember to cast force armor as often. In practice I seem to have force armor fall off during a fight/kite without this. The health regen is nice too.
Other good skill options:
Any of these can be substituted for any of the non-core abilities and still maintain a reasonably functional build.
Shock Pulse with Piercing Orb: As an alternative to seekers. Lower single target damage, but you can hit multiple targets. When kiting enemies tend to line up, so this spell will most likely make killing trash easier. It lacks some of the utility of seekers - the fire and forget style which is so nice when kiting faster elites, but if you find yourself wishing trash would go faster, grab piercing orb.
Diamond Skin with Crystal Shell: Diamond skin works best if you have high armor, high resists, and low maximum hitpoints. Generally you would substitute it for mirror image, as they serve similar purposes.
Magic Weapon with Force Weapon: A nice damage buff if you can afford to drop a defensive ability, or if you want to free yourself up for even more movement by not having a signature spell, and make up some of the damage lost.
Ray of Frost with Cold Blood: Used instead of a signature spell. Good single target damage, but not as kite friendly as seeker missiles.
Blur: If you are particularly weak defensively and the content you're fighting is managing to smoke you through force armor, consider swapping glass cannon for blur and see if that makes the difference. If the hits you're taking are maximally mitigated by force armor (only do 35% of your life) then blur is pointless.
Cold Blooded: To spite what the tooltip says, currently the Cold Blooded passive increases ALL damage done to chilled targets by 20%, regardless of the type of damage, making this an interesting choice for a passive instead of Glass Cannon.
There are no special legendary items you need. In fact this build probably requires the least gear of any build, for any class. Your priority is simply to increase your "damage" number on your character screen as much as possible, while maintaining a baseline of defensive stats.
Unlike most wizard builds for which weapon speed negatively impacts arcane power consumption, weapon speed has no real drawbacks for blizzard/hydra. As such I recommend the fastest weapon possible to reduce the time it takes you to stop and cast something while kiting. Fast weapons also gain a greater benefit from the +damage on your offhand and other sources of +damage. Stacking attack speed gear is also a good way to boost damage for this build (at least until we see what the 1.03 nerfs have in store).
Intelligence is your primary stat, and obviously you want to stack it. Weight it exactly as much as the character screen "damage" stat tells you to. There's no hidden formulas you need to know, no gotchas. You might give slight preference to intelligence because of the 10 int = 1 res all formula, but it isn't a big deal.
Crit chance and crit damage. Again weight it as heavily as the character screen "damage" stat tells you to. To spite what has been said in various places, blizzard and hydra do benefit from these stats.
Survival stats are basically whatever it takes to get force armor to kick in at full effect for most of the attacks that will be hitting you semi-regularly. Some attacks are just really nasty and you shouldn't try to be able to take only 35% from all of them, just the ones that you're likely to get hit with. Some examples are below, but these aren't hard and fast numbers, just bump up your survivability until you're comfortable and not getting wrecked. Note that if you get killed by lots of small hits rather than a big one, there's nothing (gear wise) that will really fix that:Act 1: 4k armor, 200 res all, 20k health
Act 2: 4k armor, 300 res all, 30k health
Act 3: 5k armor, 500 res all, 30k health
Act 4: 5k armor, 600 res all, 40k health
If you use diamond skin try to favor armor/resist all instead of more health. Actually for everybody it is better to increase your effective health with armor and resists than with vitality, to make full use of heals. However, it is generally cheaper to increase your EH with life (by socketing purple gems, for example).
Kite kite kite.
Approach enemies, preferably from below if you have an option, as the camera lets you see farther up-screen than down. Cast a hydra, not on them, but half way between you and them. Start shooting your signature at them if you have one, and drop a blizzard once they start to move. Blizzard has shorter range than hydra and signature spells, so pulling with it generally doesn't work that well.
If you blunder into monsters so that they see you before you have a chance to "set up" your first thing to do is to blizzard them if they are melee, or mirror image (or diamond skin if that's your thing) if they are ranged.
Kiting is a matter of continually dropping blizzards in front of the monsters coming towards you, and dropping hydras near your feet, so that they shoot the closest monster to you. Hydra positioning is important not just because you want the closest thing to you dead first, but because if the venom pools collect near the front guy, all the guys behind him have to walk through them on their way to you. This makes hydra essentially an area effect spell.
Only stop to cast signature spells if you're sure you are safe (or the monster will die in 1-2 hits). It is never wrong to cast another blizzard instead, and keep moving (assuming there is room).
For elites, you want to have a kite path cleared in advance. Generally this is just "wherever you came from." But make sure as you're clearing that nothing is going to bindside you when you come back across the same ground again kiting an elite you've run into. Make particular note of areas with nice loops you can make. Hallways that connect around in a rectangle, or circles you can make around obstructions outdoors. The ideal kite path is down-map, either to the left or to the right (better than straight down), this will let you see the enemies from farther away.
The most troublesome packs for you are generally going to be fast, invulnerable minions, and mortars. Most of the other mods are pretty easy to deal with. Even damage reflect isn't that big of a deal, you've got some regen from galvanizing ward (and maybe your gear too), and your damage is steady, you won't spike yourself into oblivion. (Although lingering damage from hydras can occasionally come back to bite you)
For mortar packs, just keep moving. Kite faster and stay as far away as you can. The enemies will stop chasing you in order to start casting the mortar animation - they do this before the mortars are actually visible. This is your queue to be moving, not shooting.
Fast packs can be tanked somewhat with mirror images thanks to illusionist. It isn't perfect, and depending on their other mods and their base monster type, they may be a skip anyway.
Invulnerable minions are often a skip. If they're a slow type you can do them, but it is annoying. Drop hydras and blizzards on the boss' head and run around in circles spamming out mirror images. Don't stop to cast signatures. If they're a fast type your only hope is to try to separate the minions from the boss. This can be done with blizzard. The slow works on the boss, but not the minions, so you blizzard the boss, then run away with the minions chasing you, and die somewhere out of the way. When you come back, the boss may be separated from the minions. Or maybe not. I usually just skip them because I don't like dying.
One of the most popular farming spots right now is Siegebreaker. Part of that was that Tyrael could solo a lot of stuff while people lay around dead. That's not necessary for us. Siegebreaker is a good run not because of Tyrael, but because there aren't any really bad monster types for us, because it is relatively fast, and usually not too hard to pick up a 5 stack on the way to him. Also Siegebreaker himself is easy, so there's that.
Heralds of Pestilence: These are often regarded as one of the nastiest monster types, but they're really quite easy for us. They can be killed by hydra / seeker missiles from out of range of their arm attack. In fact their AI won't even engage you, they'll just fold over dead. The elites have better AI and will chase you, but as long as you keep moving, kiting at a brisk pace and maximum distance, they won't be too bad. If they're invulnerable minions you pretty much have to skip them though.
Winged Moloks: These are easy. If they start landing around you pop mirror image to soak some fireballs. If you get hit by a fireball, pop mirror image again (illusionist!) to soak some more fireballs. Try to avoid the fireballs if you can, but if you get hit it isn't that bad, 35% of your life gone, you're still fine. The elites of these are about the easiest thing to deal with, you can do them even with bad mods. Just keep spamming mirror images every time you can, and simply move out of the way of fireballs as much as you can. You can stop to cast signatures a bit, but keep your eye out for those fireballs.
Blood Clan Warriors: Easy peasy, blizzard to slow, venom hydra + signature to kill. When they turn red they move a little faster, but not a big deal. Don't be a hero and try to tank them with your face, when they're red they probably won't kill you through force armor, but they'll knock you back which will stop you taking actions for a short bit, and that can often kill you. Elites are quite easy if they're not one of the three bad types for the build. If they're fast, mirror images keep them busy and you can usually deal with them anyway. If they're invulnerable minions I usually skip. If they're mortar just follow the regular best principles for mortar.
Blood Clan Impalers: They throw spears. The spears travel faster than Molok's fireballs, and are thus harder to dodge. Abuse the heck out of mirror image and illusionist to soak up spears while you kill them. For elites try to keep as much range as possible, to give you more time to see and avoid spears. If you have the room, it can be good to drop hydra and blizzard on their heads, and then run around them in a big circle. They'll throw their spears to where you used to be, and pretty much never hit you so long as you keep moving (IE don't cast signatures). This requires a fair amount of room. Fast isn't a problem with these. Mortars is actually fine, if they're casting mortars they're not throwing spears. Invulnerable minions can be dealt with too, since they're not melee the fact you can't root them isn't such an issue. Just drop your hydra on the boss and orbit / spam mirrors to avoid spears.
Blood Clan Shaman: Their fireballs are not a big deal to avoid, same as the Molok's, basically. The shield they put on other enemies is mildly annoying, but not really a big deal.
Tremors: Big, slow, not a problem. When they put up their shield get range on them, because they turn red and move fast when they come out of it. Elites of these are almost always a skip, because for some reason they are absurdly fast 100% of the time, regardless of their mods. I don't know what that's about, if it is a bug or what, but it is obnoxious. Elites of these type are quite rare, though.
Fallen+Shamans: The little fallen are of course no big deal. Blizzard to slow, mirror image if they start to swarm you, easy peasy. Things get a little more interesting when there's a shaman hiding outside of your vision range that keeps resurrecting them. Running up to him is often not practical with all the little fallen around. Cast your hydra as close to the shaman as you can. When a time comes that most/all of the fallen are currently dead, pop mirror images and move up to kill the shaman. Don't rush to kill the shaman while lots of fallen are up, or you'll get dead. Elite shamans spawn on the bridge, but not elite little guys. The elite shamans are quite easy, just like the Moloks. Their fireballs are slow and easy to avoid, just try to kite them places that don't have a lot of fallen bodies for them to res if you can help it.
Siegebreaker: Easy boss. Drop blizzards on him to slow him, drop hydras near him to kill him. When he rears up, circle around behind him and he won't charge. Stopping to cast signatures is not advisable, at least not until you're pretty comfortable with the timing. Just be patient and let your hydra kill him, you can avoid getting hit at all in the fight if you don't get greedy and try to burn him a lot with your signature.
I made a youtube video of a Siegebreaker run, for your edification. It probably isn't necessary to watch the whole thing in order to get the gist of how the build plays, but it is all there if you are bored. It wasn't a particularly good run, as I only got three stacks by the time I got to Siegebreaker, and had to go to the battlements to pick up another two - this made it a somewhat longer run than normal. I'd say 2/3 of the time I get 5 stacks clearing to siege, 2/9 the time I get 4 stacks, and 1/9 the time I get 3.
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