Splash Neptune

Lifelink
Splash Neptune does not untap during its controller’s untap step.
Pay {1} to untap Splash Neptune
{x}{u} - Tap all creatures defending player controls with mana value X or less. Put a stun counter on each creature tapped this way.
{3}{w/b} - Splash Neptune gains deathtouch and double strike until end of turn.
If Splash Neptune does not attack during its controller's turn, its controller loses 2 life.