Namosi, Triton Seacaller

Evolve (Whenever a creature enters the battlefield
under your control, if that creature has greater power
or toughness than this creature, put a +1/+1 counter
on this creature.)
Whenever Namosi, Triton Seacaller evolves,
add X mana in any combination of {u} and/or
{g}where X is Namosi's power. Spend this mana
only to cast creature spells. Draw a card.