Vine-Born Hydra

Bloom. (When this creature has 3 or more +1/+1 counters, it becomes all colors and has protection from its original colors.)
Vine-Born Hydra enters the battlefield with X +1/+1 counters.
Whenever Vine-Born Hydra attacks, target player taps a target land they control until end of turn and takes damage equal to how much mana it gives.
Hydras sure are scary.