Siddryn, the Evertail

Reach, trample
Whenever Syddryn deals combat damage to
an opponent, mill that many cards, then you
may cast a spell with mana value X or less
from among the milled cards without paying
its mana cost, where X is the number of cards milled this way.
When Syddryn, the Evertail dies, you draw three cards, then discard a card.