Body Replacement Technique

The instant before they are to be struck by an attack, the user replaces themselves with a block of wood or something similar. Because the attack does hit something, opponents may briefly believe that they've successfully struck the user. But this is merely an optical illusion and opponents will quickly notice what's happened. If users are fast enough, they can use this brief lapse in the opponent's attentions to stage a counterattack. Alternatively, this is a good opportunity for users to escape.

The Body Replacement Technique can evidently only be used in response to what would be harmful attacks: Pain only escapes from Jiraiya's Wild Lion's Mane Technique when Jiraiya tries to kill him with it; when Jiraiya uses the same technique to only keep Pain restrained, Pain remains captured.

Trivia

 * This technique is based on a real-life ninja art, kawarimi, where ninja substitute themselves with anything that can be mistaken for them (such as a dummy or a mannequin).
 * As it means "a quick shift in position, or adaptability to changing circumstances", it is also utilised in Sumo.
 * In other series, abilities similar to the Body Replacement Technique are sometimes referred to as the (not to be confused with the Empty Cicada Shell Technique, which uses the exact same kanji). This name refers to the empty shell a cicada leaves after moulting.
 * Instead of the usual blocks of wood, Killer B uses the Eight-Tails' severed tentacles to mask his escapes.
 * In Naruto: Clash of Ninja 2, Akamaru substitutes himself with a bone rather than a block of wood.