I noticed that, after some PvP action in both Imperial City and Cyrodiil, the Necro Flame Skull skill (more specifically, the Richochet Skull morph, I have not tested it yet with Venom Skull) bugs out. What happens is that I reach the necessary 3rd cast to make it bounce (and do AoE damage plus generate a corpse due to Gravelord's Sacrifice), but all the extra effects don't happen: No 33% extra damage, no ricocheting, no corpse, no aoe damage. The projectile just looks like a normal, first cast of the skill, doesn't matter how many times I cast it, and a persistent 3-skull effect is permanently showing up on my buff bar (the same you get when you are ready to cast the empowered 3rd cast skull). You can get rid of this effect only by dying or logging out.
As far as I can tell, this only happens in PvP, and I'm 90% sure it is related to some form of interaction with people dodging my skulls (it happens a lot, since they are slow projectiles and people see them from miles away).
So, yes, yet another issue with Necro, making the class less and less effective in PvP. Please, ZOS, look into this.