I messed around with a bunch of different setups on my necromancer:
http://nevergrind.com/nevergrounds/inde ... ter=RayyakDark Elf seems like a no brainer here. Necro is super squishy, and you'll run out of CDs for heals and fears in longer fights and you might require the racial ability to survive that fight. I know there were some times where I would have died without it.
In the early levels, buffing up your pet is a good idea, but once you unlock the full tree and get all the skills, I highly recommend buffing corpse explosion so it can activate from poison damage.
I got a logitech G700 mouse, and I'm able to make custom keybinds which really help a ton with necromancer particularly with getting the most out of corpse explosion procs.
General strategy:
I made a keybind to cycle targets and cast asystole so I got greater odds of getting corpse explosion procs. I got another keybind that activates corpse explosion ASAP. While at the same time I manually pump bone spirit (fireballs) and use my fears and healing abilities when needed. The good thing about necromancer is they can do physical or elemental, so those certain combos that screw one or the other aren't that bad.
When things are going well, you'll be pulling mobs very quickly, and you'll be raining fireballs with corpse explosions going off simultaneously, and you'll be doing insane AOE DPS. The 20% chance to counter with fireball is VERY good when you got 3-5 mobs on the screen attacking, and buffing cast speed helps a lot as well. Try to get your cast speed for fireball to below .6 secs, like .56 or .57 is good. There are times when I get counter procs and machine gun like 3-4 fireballs. If those are regular mobs, they're DONE.
My general take on necromancer is they aren't good for really huge chains, like into the hundreds, but can easily do a chain of 25 or 30 really quickly. When I plan on chaining and fighting multiple mobs on the screen, I bring a shield with 24% block rate, because it increases my survivability and allows me to extend a chain further. I'm not sure what the optimal shield is for a caster, but I was using a Steelclash, and it works pretty well. I haven't found any epic tier unique shields yet.
By the way, I don't grind in Nimgall, I fight the mobs at Viston's, because they're weak vs fire and generally got lower HP. Most of them are casters as well which are considerably easier for necromancer to deal with than heavy hitting melee mobs that attack super fast and stun. The fire weakness also typically transfers to champion mobs which makes them easier to drop, unless they show up with Chromatic, but I can take those out with corpse explosions. I don't plan on getting to 99 on my necro, but I do plan on doing some chains in the 10-30 range @ viston's really quickly to farm some gear up. I got freaking wrecked in Nimgall when I tried to fight multiple targets on the screen.
I don't have 20 points in asystole because I thought the 15% magic damage with shields up was better than it is in reality. To clarify you need Arch Shielding AND Diamond skin up to get the 15% bonus. And because Diamond skin is trash, and burns up on a couple hits, you are almost never going to have that 15% buff. I think Diamond skin needs to be buffed, because I only get 500 damage absorb with 400 abjuration. And of course, buffing asystole's damage isn't crucial because I'm mainly using it to proc corpse explosion.
Overall, Necromancer is decent. I wouldn't say its OP, because necros are glass cannons.