King T'Challa, the Panther

Assemble~ When another Avenger creature enters
the battlefield under your control, put a charge counter on T'Challa
T'Challa gets +1/+1 for each charge counter on
him
Whenever T'Challa attacks, you may remove any number of Charge Counters from him, if you do:
deal X damage to each creature your opponent controls, where X is the number of counters
removed this way