Mana Snatcher Shark

Flash, Depth Delver
Wellspring {r}{g}{r/g}{r/g}: Mana Snatcher Shark
absorbs all coloured mana from target opponent
and has +1/+1 for each mana stolen this way.
Wellspring: Wellspring is activated if enough
mana is left after casting cost
Depth Delver: if target attacking opponent has islands, this creature can block two creatures