Bolg, Castellan of Gundabad

Horde - At the beginning of your upkeep, if you control five or more creatures, put a corruption counter on Bolg.
Corruption 2 - Bolg enters the battlefield with two corruption counters on it. At the beginning of your upkeep, remove a corruption counter from Bolg. When the last is removed, Bolg loses all abilities.
Whenever Bolg attacks, target creature gets -X/-X until end of turn, where X is the twice the number of corruption counters on Bolg.