Myr Battlesphere

When Myr Battlesphere enters the battlefield,
create four 1/1 colorless Myr artifact creature
tokens.
Whenever Myr Battlesphere attacks, you may
tap X untapped Myr you control. If you do,
Myr Battlesphere gets +X/+0 until end of turn
and deals X damage to the player or planeswalker
it’s attacking.