Clay-will slow down quite a bit, but only 1 target, not good for PvM
Blood-leech, but i guess he is still very killable
Iron-thorns, not enough, as monster dmg is ridiculously low compared to monster life
Fire-good dmg in paper, but i think its AR is TOO DAMN LOW to even hit things often enough to actually hurt, also, mana cost is astronomical (not good to face bosses)
I recently let my lvl 84 hardcore summoner die because the phone rang and I didn't see some dolls before I left.
I soloed the entire game (he was a guardian), with mediocre gear (although the day before he died I did find a Leviathen for his merc).
The skill distribution I used was as follows, I would not change it a bit.
max raise skeleton
max skeleton mastery
10-15 amp damage
1 clay golem
1 golem mastery
5-10 summon resist (it's nice in hardcore)
1 decrep, and precursors
5 or so dim vision.
By the time I died, I was basically running hell pindleskin, shenk, eldritch, meph and the pit. I did occasional baal runs, but black souls scare the hell out of me so I was going to wait to have more points in dim vision before I started doing them in earnest.
Explaining my skill choice:
RS and SM are obvious
Amplify damage...it doesn't improve the actual curse to put more points in it, but I found it much easier to clear crowds if I didn't have to worry about cursing them more than once. A huge area of effect and decent duration means that you can concentrate more on getting those bodies exploding as soon as they fall, rather than having to spam curses to be sure that all the monsters are taken care of.
Corpse explosion is the god of crowd control. Yes, it's true that a good volley of lightning fury might take out a village of carvers faster, or that blizzard might be quicker at taking out the minions of destruction, but with a decent enough radius and a little amp damage, there is almost nothing in the game that can survive a few spatterings of shattered demons. I'd like to see a light javazon do that with black souls, or a cold sorc take out frozenstein like a necro can.
Decrepify...some people think it is better in every way that amp damage, and question me as to why I don't max it. All points in decrep do is add duration, no radius. This makes it poor for crowds. Also, although it does amplify damage aswell, it is by 50%, as opposed to the 100% amp adds. Yah, it slows and weakens bad guys, but that doesn't include spell attacks. Truthfully, with just a few +skills, your skeletons shouldn't have trouble surviving anything, making the added benefits kinda useless when fighting most monsters.
The obvious exception is bosses, who, when confronted with your melee minions, do powerful melee attacks, that are very handy to slow down. This is the only time I used decrep.
Clay golem....I'm sorry, baal gets slowed by 50%. What was the question?
summon resist....more necessary on HC, where losing your meat shield can mean an instant end to your sanity and D2 career, but it is also nice for running meph, when he has dark lords spamming meteors all over your minions. One point minimum is a must.
Dim Vision...is more useful in HC, where dying is everything, but it is handy once you have it up to a bit of a duration, as black souls and the like are really annoying when your skeles are bulldozering through the packs of monsters half a screen away. Also, preventing oblivion knights and witches from cursing your skeles is ever handy. This is where I planned on putting the rest of my points, until I died.
Stuff I didn't use:
None of the golems are worth maxing when you have an army of skeletons. The skeles will do astronomically more damage than the golems can hope to, and your +skills should give them enough life to survive a decent amout of time.
Blood golems die easily, and cost you life as much as give it to you (I find). You shouldn't need life stolen for you with your massive meat sheild anyways.
Fire golems do not do enough damage to make it worth it in crowds, and clay golems are much handier vs bosses (to keep the skeles healthy)
Iron golem with an IK maul is a great choice for speeding up the killing of bosses, absolutely useless elsewhere though. And no, IK mauls are not something to cry over if you use them. Other good choices are Executioners Justice, Rattlecage, Bonesnap. Ethereal ones make him extra cool.
If you want, a point in blood is arguably a decent idea for the life bonus to your clay. I didn't bother.
Revives, mages....some people swear by them, I hate them.
Revives are too short lived, stupid and annoying to keep maintained for me to bother with. My skeletons do plenty of damage as it is.
Mages are uberhandy for when you are surrounded by PIs. Or, you can just be patient, use a lot of amp damage, and them blow them all to hell once you are presented with a corpse. They just don't do enough raw damage to make me feel they are worth all of the annoyances of having them get in the way of your skeles in tight areas.
Bone armour...takes too many points to make it worthwhile (since marrowalks are useless), in my opinion. Some people disagree, and I admit, if you really don't want to put lots into curses, this has the potential to save your *** on occasion.
All poison and bone skills....useless without like 60 points in their trees. Just don't bother.
Attract...a good substitute for Dim Vision. it's really your choice. I like em both.
lower resist...I hate mages. I like physical damage from CE and my merc and skeles. It just isn't worth it to me.
Life tap...when killing hell baal for the first time, lister killed 1 skele, and baal killed my golem once. This is not needed to keep them alive.
iron maiden...maybe useful if you are worried about getting pked by a melee player??? I don't know, I've never used it.
I've heard of someone makeing and iron gollum with an insight polearm.
He figured the mana regen was worth the occasional sol to make a new one.
Would the MF add to yours if the gollum did manage a kill?
You can't make an IG out of a bow can you?