Muxus, Goblin Lord

You may tap a goblin you control with CMC 5 or less to pay for {1} for this spell. Those goblins don't untap during your next untap step.
Muxus, Goblin Lord gets +1/+1 for each goblin with CMC 5 or less you control.
Goblins with CMC 5 or less get +1/+0.