Corrupt
(When a creature you control is targeted by Ungodly Oathdealer, put a Corruption counter on it.)

,

: Target creature gets +2/+1 until end of turn.
When Ungodly Oathdealer leaves the battlefield, remove all corruption tokens on creatures you control and put an equal number of -1/-1 counters on them.
For Challenge # 143 using the keyword 'Corrupt'. I'm not sure about this card exactly, since the abilities seem pretty swingy. But I like the idea that there's a price for dealing with this creature. Maybe use discard or lose 1 life in the future... easier things to mitigate than a potential board wipe (you'd think that would take time... but if there's a lot of corruption in the set, then that downside is probably too much.)