Rimeru Tempest

Urtet, Remnant of Memnarch

Whenever you cast a Myr spell, create a 1/1 colorless
Myr artifact creature token. At the beginning of
combat on your turn, untap each Myr you control.

{w}{u}{b}{r}{g}, {t}: Put three +1/+1 counters on each
Myr you control. Activate only during your turn.