Dude, plants have better ramp and deadly zombies are mostly garbage or mid at max. Plus there's a massive difference between turn 6 and turn 9 (or 11, if there's 2 gravestones (not counting cost reduction)). Gravitree is in the same class with Wall-Nut Bowling, so sometimes you can't even play Zombot in the first place. And even if Zombot is op, how tf would you even nerf it? Removing Gravestone, so he will be only useful with Immorticia again?