If you control a "Blackwing" monster other than "Blackwing - Kris the Crack of Dawn", you can Special Summon this card (from your hand). You can only Special Summon "Blackwing - Kris the Crack of Dawn" once per turn this way. Once per turn, this card cannot be destroyed by Spell/Trap effects.
Unlike Bora, Kris can only be special summoned once per turn, so I think people won't bring more than 2 copies of this card. Also its effect isn't that great, sure it can protect itself against Treacherous but obviously your opponent would prefer target your boss monster instead of Kris