Myr Battlesphere BRC/151

Set: The Brothers' War Commander
Collector Code: BRC/151
Name: Myr Battlesphere
Type: Artifact Creature — Myr Construct
Oracle text: When this creature enters, create four 1/1 colorless Myr artifact creature tokens. Whenever this creature attacks, you may tap X untapped Myr you control. If you do, this creature gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.
Rarity: Rare