Treacherous Kelpie

Mount (Tap a wizard you control: Treacherous
Kelpie gets +X/+X equal to the tapped creatures
power until end of turn. Activate this ability only
any time you can cast a sorcery and only once per
turn.)
Treacherous Kelpie cannot be blocked.
If Treacherous Kelpie deals combat damage to a player, Treacherous Kelpie destroys the wizard
that mounted it.