Ninja of the Deep Hours

The ninjutsu ability can be activated only after blockers have been declared. Before then, attacking creatures are neither blocked nor unblocked.

If a creature in combat has first strike or double strike, you can activate the ninjutsu ability during the first-strike combat damage step. The Ninja will deal combat damage during the regular combat damage step in this case, even if it has first strike.

As you activate a ninjutsu ability, you reveal the Ninja card in your hand and return the attacking creature. The Ninja isn't put onto the battlefield until the ability resolves. If it leaves your hand before then, it won't enter the battlefield at all.