Unstable Concoction

{t}: Add {c}
{1}, {t}: Sacrifice this artifact. It deals X damage to any target, where X is the number of potion counters on this artifact. Costs {1} more for every potion counter on this artifact. Activate only as a sorcery.
At the start of your end step, put a potion counter on this artifact. Then, if there are 6 or more potion counters on this artifact, sacrifice it. You lose 6 health.