This creature enters with four +1/+1 counters on it. Whenever this creature attacks or blocks, remove a +1/+1 counter from it. If you do, it deals 1 damage to any target. {T}: Put a +1/+1 counter on this creature.
2021-03-19
If Clockwork Hydra leaves the battlefield while its trigger is on the stack, you can't remove a +1/+1 counter from it, so it won't deal damage.
2021-03-19
If the chosen target is an illegal target by the time Clockwork Hydra's triggered ability tries to resolve, the ability doesn't resolve. You don't remove a counter from Clockwork Hydra.