Frodo, Ringbearer

Frodo, Ringbearer can't be blocked.
At the beginning of your end step, put a corruption counter on Frodo, Ringbearer.
If Frodo has three corruption counters on him, any opponent may pay {5}. If they do, they gain control of Frodo.
{3}{b}: remove a corruption counter from Frodo, Ringbearer.
I told myself I would not succumb. Now, I'm not so sure.