Rakdos, Live at the Guildpact

Whenever a creature enters the battlefield under your control put a rock counter on Rakdos, Live at the Guildpact
Whenever a creature you control is put into the graveyard from the battlefield all opponents sacrifice a number of creature equal to the number of rock counters on Rakdos, Live at the Guildpact. Remove all rock counters from Rakdos, Live at the Guildpact.