problem for pvp is, you dont have real answers against shields(fire and aether often used) or land destruction(graboids), and you are not fast enough to outrush opponent. also pests prevent you from devouring, all in all i think you need to splash a 3rd element.
Well every deck has a counter, reverse time can cut down graboid rusher
While knowing they have quicksand, dont play every tower at once
Against shield is hard, but 3 pharoah out = 3/3 turn 1 scrab, then 3/6, 3/9 firewall wont hurt it at least
Not to mention you can keep eating
Besides, this more for fun then for deadly kills