I've been having so much fun with my summoner witch that I thought I would share her build with the community. She's a pure summoner (and by that, I mean I don't cast ANY offensive spells myself) that debuffs mobs via curses and let's the minions clean house.
Disclaimer: This is softcore tested only, but I'm sure it would prove viable on Hardcore as well (you'd probably want to pick up more life/resist nodes earlier on as pointed out by some of the responses in this thread). Currently progressing through Act 2 Merciless; bosses are no issue with this build.
Here is my current build at LV55:
...and eventual end-game build (111 points):
1. Minion Instability (get this as soon as humanly possible, foundation of this build)
2. Necromantis Aegis (by late Act 3 normal or Act 1 cruel you should go for this)
(note: I've read a lot of negatives about this, but it's worked out fine with my build. Since I don't ever a) cast dmg spells or b) take dmg (rarely) it's a boon to give the benefits of my shield stats to my minions. They survive longer. Still in need of a decent shield, but I'm more of a fan of NA then opting against it. YMMV.)
3. Hex Master (personal choice, but I hate recasting curses)
4. Whispers of Doom
5. Eldritch Battery (will grab very late game to run 6+ auras)
Make sure you also grab the +1 to Spectres (near the minion instability keystone) as soon as you can. Don't underestimate how powerful 2 spectres can be.
With every passive minion node taken, I've currently got 8 zombies, 12 skeletons, and 2 spectres.
I run 4 auras currently (Discipline, Wrath, Anger and Clarity) and am toying with taking Eldritch battery so I can run 2 or 3 more.
My curses are Enfeeble and Vulnerability, solid debuffs. Until I got the Whispers of Doom keystone, I was just running Enfeeble.
My gear and gem layouts are:
1.Raise Zombie linked to the following gems: minion life/minion dmg/added lightning dmg
2.Raise Spectre linked to: minion dmg/added fire dmg/added lightning dmg
3.Raise Skeleton linked to:
4. I'm running Enfeeble and Vulnerability with enhanced area effect:
I never ran into any trouble until I hit Act 3 normal. I had stretched myself to thin trying to lay the path for my build without picking up enough passive minion life nodes. Once I respecced and dumped points into the passive life nodes, I was fine. By end of Act 2 cruel, you should have grabbed every passive minion node (+minion/life/dmg) on the board.
My strategy is simple - drop a totem down (or summon skeletons manually) to create your meat shield of disposable skeletons. They'll do surpisingly decent damage (or blow up and wreck even more havoc) and allow your zombies and spectres time to really dish out the pain. Your zombies shouldn't be dying, at least not all at once (note: early game, expect them to die quickly. They don't have a lot of hp. By the time your Raise Zombie gem levels to 7 or 8, the hp starts ramping up significantly though). If they are, you probably need more passive minion life nodes, or are pushing faster than your current gear/gems/level will allow.
Best part about this build is that the areas that are normally super annoying based on the monsters (A2 pyramid chaos shooters/snakes, A3 Lunaris temple tentacle breast shooters, etc) end up being extremely easy areas once you're rolling with 2 of those spectres. Turn those mobs to your side and laugh as they mop the floor.
This build is not a super fast, clear the entire map in 5-minutes set-up. If you're looking for an extremely fast and efficient farming build, this is probably going to be far slower than you're going to want. You'll spend the majority of your time summoning your skeleton army and cursing mobs, then standing around waiting for your minions to clear everything out.
It's extremely rewarding if you truly enjoy a pure summoner-heavy build though.
Thoughts on end-game build:
I'm going to take Eldritch Battery so I can roll 6-7 auras around level 65 - 70; currently I'm taking all the +hp nodes so I can forego ES.
Questions or thoughts?