LeBron, My GOAT

Trample, Haste, Hexproof, Indestructible
LeBron enters the battlefield with X +1/+1 counters
on him.
When LeBron enters the battlefield, add X mana of
any color to your mana pool. This mana doesn't
empty as steps and phases end.
Whenever LeBron attacks add {w}{w}{u}{u}{b}{b}{r}{r}{g}{g} to your mana pool.