Riku, the Double Helix

Whenever you cast an instant or sorcery spell,
you may pay {u}{b}. If you do, draw a card for
each card in your hand and you lose life equal to
the number of cards in your hand.
Whenever another nontoken creature enters the battlefield under your control, you may pay {b}{r}. If you do, put a double strike and a
trample counter on that creature.