Bumi, Eccentric King

When Bumi, Eccentric King enters the battlefield, create 3 colorless artifact tokens called "Boulder."
Bumi gets +0/+1 for each artifact you control.
{x}{g}{g}, Sacrifice an artifact: Bumi deals X
damage to target creature or planeswalker.
If X is equal to or greater than Bumi's
power, create a Boulder token.