Nightstalker Engine

Whenever this creature attacks, you may tap target creature.

Vigilance

Reach (This creature can block creatures with flying.)

T: Target creature gets +2/+2 until end of turn. Activate only during your turn, before attackers are declared.

When this creature blocks a creature, destroy both creatures.

Flying When this creature dies, you may shuffle it into its owner's library.

Flying When this creature enters, you gain 3 life.