@davidy22
50 purify counters would be impossible to get I think the creator means a whole diffrent type of counter called "Regeneration Counter" which would need a way to be countered. Imagine someone though with like 50 "Regeneration Counters" and 6 SoG with a shield like dusk mantle with it being enchanted it would take sooo long to kill that person and you probably wont unless you have Lava Golem etc reached 100 plus attack. I would just quit the match because in the end that one match wouldn't be no where near worth all the time to take down that opponent.
That's why it should be some type of counter for this card like maybe if you kill the Neriad all the "regeneration counters" that single creature created also dissappear. Off topic this card has some nice art to it.
This shouldn't even be a question, really. If you use Purify, you have two regeneration counters. If you take one poison damage, you now have one regeneration counter. That is already implemented in the game.
It is entirely possible to have 50 regeneration counters. You are in a PvP match, and you and your opponent both play three Quantum Towers. Once you have the required quanta, you then both play one Eternity, one Shield, one Blessing, two Neriads, Aflatoxin (on the second Neriad.) You both then play two Time Factories. Every turn, you reverse-time one Malignant Cell. After a few turns, you both have a large amount of regeneration counters stacked up. Tada, absolutely possible.
You shouldn't need some card that magically destroys this card's effect. That is what creature control is for. When you kill a Lava Golem, you don't magically regain all of the damage that the Golem did as health. After you destroy a Shard of Gratitude, they don't lose five health for every turn that it was active.