Kojj, Calamity of Annihilation

When Kojj, Calamity of Annihilation enters the battlefield, each player exiles two cards from his hand face down. As long as Kojj, Calamity of Annihilation is on the battlefield you may cast the exiled cards and spend mana as it was mana of any color.
Whenever you cast a card from exile, Kojj, Calamity of Annihilation deals 1 damage to any target.