) that's been cast for its awaken cost of 
in the mana cost of the card you discard, that X is 0. Any Kozilek, the Great Distortion refills a depleted hand and then turns that hand into interaction. Casting it can draw you back up to seven cards, while its activated ability discards a card to counter a spell with the same mana value. A ramp deck that spent most of its resources reaching ten mana can suddenly hold both new threats and answers.
The draw is a cast trigger, so putting Kozilek directly onto the battlefield does not provide it. The trigger also checks your hand size when it resolves. You are drawing the difference between the cards then in your hand and seven, rather than automatically drawing seven fresh cards. The two colorless symbols in its cost require actual colorless mana sources.
A varied mana curve makes the counter ability more flexible. A land can counter a spell with mana value zero, while a spare two-mana rock can answer a spell with mana value two. The ability does not require mana or tapping Kozilek, allowing it to work immediately if you have a suitable card. Your hand becomes a collection of possible matches rather than a universal counterspell.
Menace and a large body let Kozilek pressure opponents while you protect the board. In a colorless commander deck, utility lands and mana rocks support the cast, and reusable card draw helps replenish discarded answers. Avoid filling every slot with expensive threats: smaller cards help early development and give Kozilek useful values to discard when opponents try to interrupt your next turn.
