Cirilla Riannon, the Swallow

Flash, Firststrike, Protection from black
When another Legendary creature enters the battlefield Cirilla Riannon, the Swallow gains
+2/+0 until the end of the turn.
When Cirilla Riannon, the Swallow deals combat damage to a player untap it.
"Hatred and vengeance blinded me ... But I shall
stand before them in humility. I shall remember the expression in their eyes. I hope the memory of those
eyes will stop me making a similar mistake."