Butterflying, also known as wall climbing, sword canceling and sword climbing, is a glitch present in Halo 2 and Halo 3. The glitch is a form of Sword Flying, and it allows two cooperating players to fly through the air.
Have one player (Person A) jump on top of the other player's (Person B's) head. Person A should repeatedly jump while standing on Person B. Person B should, while looking up at Person A and holding an Energy Sword, rapidly press X and B. The button combination uses a reload to "cancel" a sword lunge (sword canceling), allowing the lower player to "fly."
More precisely, Person B ends up lunging at Person A, but canceling the lunge before the blow actually hits. The end result is that Person B moves upward, pushing Person A upward as well; Person A, however, is not killed by the lunge. When Person A jumps, they put distance between themselves and Person B, preventing the lunge from being an instant hit and kill. The two players can simply repeat the trick ad infinitum to achieve greater heights.
Note that Person B may use any weapons, though the Energy Sword is recommended.
An Expert and a Beginner
It is relatively easy for an expert and a beginner to perform the trick. The expert (Person A) should have an Energy Sword. Both Person A and their companion (Person B) should find a right-angle corner; Headlong has many such corners.
Person A should walk into the corner. Person B, the beginner, should jump onto Person A, and should continue jumping until they are stuck in the corner. When Person A is able to run around without causing Person B to fall, the trick may be performed.
Person A has to press A, B, and X in sequence as fast as possible. Person B must simply button-mash the A button. Note that for long climbs (such as when two players attempt to scale a tall building), Person A may have the additional task of moving forward into the building as they button-mash, to prevent Person B from slipping out of the corner. Ideally, a ruler or other item would be used to hold the thumbstick forward, so that both of Person A's hands are free to execute the button combination.
- Y may be used in place of X when performing the button combo. This is actually safer, as it decreases the chance of the top player being accidentally assassinated.
- An Overshield can also prolong the top player's survival.
- Making the players turn in opposite directions can also prevent a potential assassination. Turning off auto look centering can help.
- The bottom player must be sure to keep looking at the top player.
- The right trigger may be used in place of B, though it would likely be more difficult to use.
- It is wise to rest between consecutive attempts at butterflying tall structures. The repetition involved in the trick could tire out or strain a player's hands.
The Halo 3 method is identical to the standard Halo 2 method, save for the difference in buttons -- RB is used instead of X.