Thunder Breathing

Creatures you control have the following abilities. You may only activate one of these abilities every turn:
Thunder Breathing, First Form: Thunderclap and Flash - Remove a Breath counter from this creature: this creature gains haste, trample, and vigilance, and can only attack alone this turn.
Thunder Breathing, Third Form: Thunder Swarm - Remove a Breath counter from this creature: this creature gains double strike and myriad.