Zem is effected by a huge bug: he deals true damage(ignoring armor and magic resist) with his zombies while they keep spawning and giving him buffs.
Basically, there is an high chance that tanks are useless against him, while he usually kills the whole opponent team in less than 30s!
If he gets no bugs, he dies in 5-15 seconds dealing no damage!!
We reported this bug to FB support and they said that we had to report this here.
Please, fix it because he's killing whole 7* orange+1(3+ items full enchanted) teams being a 2* orange(1 item not echanted)!