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)!
time for myth busters!!!
Most screenshots that you provided are showing wrong data to consider Zem bugged.
First - his skills doesn't correspond much with his stats, thats why his 2 stars aren't downhill his power a lot... ZOmbies - doesnt need his stats, and his AoE damage depends on magic attack. 1 star gives 50 mattack maximum f.e.
Second - his 2 AoE skills does damage to front and mid row and SUMMONS!!! thats why his scaled damage at the end of the fight vs 4-front rows and/or 2-summonners and/or 3-mid rows is quadro bigger............. dont you see it?)))
Garrick can crit for 100k but if enemy had 5k - his scaled damage is 5k. Zem deals damage to full-HP summons and spread AoE to all full-HP enemies at one row, and its considered to scale his overall damage high.
My guild fights for first arena places and he isn't bugged or OP from replays I've seen.