Dr. Doom armor
The amount of armor that Dr. Doom has is ridiculous, not to mention his crit resistance. He practically takes little to no damage. Was watching Seatin's gameplay video a while ago and he practically tanked an SP3 from an ACT 6 champion, without so much as losing a mere 20% or so of health. Imo, this is pretty OP. The only counter I can currently think of is Havok, since he deals mostly energy damage, but even that is more or less mitigated. He should be toned down a bit in terms of armor. The rest is good as it is.