Ready or Not

Ready or Not
SpellCost: 4
Ready one of your units.
Opposing exhausted units don't ready during their next ready step.
PurplePresent Magic

Card-Specific Rulings
Readying one of your units CAN allow it to attack twice in a turn. (Attack with a unit, which will exhaust it. Play Ready or Not on that unit to ready it, then you can attack with it again.) — Sirlin
If a unit has the readiness keyword, using Ready or Not on it won't let you attack twice in a turn with it because readiness specifically says you can't do that. — Sirlin