Najeela, the Blade-Blossom Bonus

SLD Secret Lair Drop

Whenever a Warrior attacks, you may have its controller create a 1/1 white Warrior creature token that's tapped and attacking. {W}{U}{B}{R}{G}: Untap all attacking creatures. They gain trample, lifelink, and haste until end of turn. After this phase, there is an additional combat phase. Activate only during combat.