Silyuus, the Blind Sin

Trample, hexproof
At the beginning of your upkeep, whenever you cast a spell, and whenever another permanent you control enters the graveyard from the battlefield put a +1/+1 counter on Silyuus.
Remove X number of +1/+1 counters from Silyuus, {t}: Skip your attack phase, and each creature your opponent's control get -X/-X until end of turn.