Double strike, indestructible
Oketra the True can't attack or block unless you control at least three other creatures.
{3}{W}: Create a 1/1 white Warrior creature token with vigilance.
Once Oketra has attacked or blocked, it will remain in combat even if the number of other creatures you control becomes two or fewer.
You don’t have to attack with three other creatures for Oketra to be able to attack. The same is true of blocking.