So, I'm a lvl 70 fire wall sorc and I'm currently stuck in hell. I'm interested in any advice you could give me on what to focus on improving (and possibly how). I have lvl 21 fire wall, lvl 21 glacial spike, 21 warmth, lvl 2 frozen armor, and the rest is in fire mastery and pre-requisites. The problem I have is the Den in Act 1 hell. I can clean up the whole level, except one unique which is always immune to cold, and my fire wall does very very little damage to him. My merc (barb from normal) gets killed almost right away, and I can't tank long enough. What am I doing wrong? I guess my weakest point is my gear, my current defense is 940 (when I cast frozen armor). My resistances are also not that great, but not that terrible either (fire 70, cold 75, lightning 33, poison 28). Still, my main concern is the fact that I don't seem to have a good spell to kill this monster, even though I've maxed out my main skills. Any advice?
Fire wall requires theatrics in terms of positioning. You basically have to stand perpedicular to the mob, cast it, then stand at the far end so it has to walk thru your firewall sideways and get burned up. Mercs can get hammered in hell difficulty, make sure your merc is your level by shopping for a new one. Equip the merc with either a woestave or kelpie snare. Those weapons have an awesome attribute called slow monsters which can really neuter the target and help your merc tank while firewall burns him down. You could try the spellsteal axe to cast decrepify on top of it. You could get the runeword with summon 5 spirit wolves to distract the mob long enough to die in firewall. You could get the runeword with clay golem to slow the target.
Alternatively, i find the best cold / fire sorc for questing is frozen orb / hydra. I enter hell difficulty at level 71, which is where you are at. You can stack 5 hydras at a time doing 300 dmg per shot at level 71 with my build which adds up. 300 dmg x 3 heads x 5 hydras. Hydras can kill in hell, somewhat slower than other fire spells but you can just stand one screen away, start dropping hydras and itll die without you even seeing it.My build is 17 orb, 10 cold mastery, max hydra, max fire mastery, then dump points in fireball. 1 point in teleport, frozen armor, static. spirit crystal sword, +2 skills ammy and hat. By level 90 youve got a strong orb that smashes anything not immune, a hydra doing between 400-500, a strong fireball as a backup killer, and you even had to drop 1 point in enchant on the way which you can use to boost your merc and party members. With +11 skills i think hydra does over 1000 per shot. A pack of 5 hydras will then do 15k dmg.