Graskov, mage of irritation

Discard your hand: exil the top X cards of your library where X is the number of cards you discarded that way. You may cast one of those card without paying it's mana cost, put the rest on the bottom of your library in a random order
{1}{u}{b/r}, discrad a blue, black or red card: counter target noncreture spell if you discarded a blue card.
If you discarded a red card, Graskov deals X damage to any target where X is the discarded card's converted mana cost.
if you discarded a black card, spells a