Dau'ak, the Flowing River

Dau'ak costs {u}{u}{u}{u} less if cast during an extra
turn.
Flying, Vigilance
{u},{t}: Counter target spell. The owner of that
spell adds X mana of any combination of colors
to their mana pool, where X equals the countered
spell's converted mana cost. Dau'ak deals 3
damage to you.