Koma, Nemesis of Toralf

Shroud
When Koma, Nemesis of Toralf enters the battlefield, abilities of your opponent's cards cannot be activated.
At the beginning of each upkeep, exile a card from turn opponent's graveyard, it can be cast until the end of that player's turn, if not, create a Serpent token whose power and toughness is equal to the mana value of the exiled card.