Choose odd or even. Destroy each creature with mana value of the chosen quality. Then gain control of all creatures until end of turn. Untap them. They gain haste until end of turn. (Zero is even.)
If a creature has
in its mana cost, X is 0 for the purpose of determining its mana value.
You’ll untap all creatures, including those you already control. They’ll also gain haste even if they were already untapped.