Secret Lair Drop

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

"As the experimental population grows, so do the number of myr. It's a perfect equilibrium."
—Memnarch

Battlebond

Whenever a nontoken creature enters the battlefield, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Darksteel

Whenever a nontoken creature comes into play, if Genesis Chamber is untapped, that creature's controller puts a 1/1 Myr artifact creature token into play.