Snorlax, Slumbering King

Trample
Snorlax enters the battlefield tapped with four rest counters on it. At the beginning of your upkeep, don't untap Snorlax and remove a rest counter from Snorlax and add {c}{c} to your mana pool, until end of turn this mana doesn't empty from your mana pool as steps and phases end. When Snorlax has no more rest counters on it you may untap it as normal.