Dreakaz, the Threat Below

Dreakaz, the Threat Below costs {2} less for each spell target opponent cast during his last turn.
Whenever a player draws any number of cards,
he or she must discard the rest of their hand.
Until end of turn, this player may cast spells discarded this way from his or her graveyard.
Each time a player discards a card, create a 1/1 colorless Eldrazi Scion. It has "Sacrifice this creature: Add {c} to your mana pool."