NinjutsuNinjutsu is an activated ability that functions only while the card with ninjutsu is in a player’s hand. “Ninjutsu [cost]” means “[Cost], Reveal this card from your hand, Return an unblocked attacking creature you control to its owner’s hand: Put this card onto the battlefield from your hand tapped and attacking.”
The card with ninjutsu remains revealed from the time the ability is announced until the ability leaves the stack.
The creature put onto the battlefield with the ninjutsu ability enters attacking the same player, planeswalker, or battle as the creature that was returned to its owner’s hand.
Commander ninjutsu is a variant of the ninjutsu ability that also functions while the card with commander ninjutsu is in the command zone. “Commander ninjutsu [cost]” means “[Cost], Reveal this card from your hand or from the command zone, Return an unblocked attacking creature you control to its owner’s hand: Put this card onto the battlefield tapped and attacking.” (CR 702.49) (
, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Double strikeDouble strike is a static ability that modifies the rules for the combat damage step. (See rule 510, “Combat Damage Step.”)
If at least one attacking or blocking creature has first strike (see rule 702.7) or double strike as the combat damage step begins, the only creatures that assign combat damage in that step are those with first strike or double strike. After that step, instead of proceeding to the end of combat step, the phase gets a second combat damage step. The only creatures that assign combat damage in that step are the remaining attackers and blockers that had neither first strike nor double strike as the first combat damage step began, as well as the remaining attackers and blockers that currently have double strike. After that step, the phase proceeds to the end of combat step.
Removing double strike from a creature during the first combat damage step will stop it from assigning combat damage in the second combat damage step.
Giving double strike to a creature with first strike after it has already dealt combat damage in the first combat damage step will allow the creature to assign combat damage in the second combat damage step.
Multiple instances of double strike on the same creature are redundant. (CR 702.4)