Nyx, Daughter of Twilight

Whenever a creature dealt damage by Nyx,
Daughter of Twilight dies, draw a card.
Whenever Nyx deals combat damage to a player, choose one —
• Discard a card, then draw a card. Nyx deals X
damage to any target, where X is equal to the
mana value of the discarded card.
• Exile the top card of that players library. You
gain life equal to its mana value.