Haste

Haste (ヘイスト, Heisuto) is the Black Mage's side special move in Super Smash Flash 2. The Black Mage slowly summons an image of himself in front of him that quickly disappears if the purple line in front of himself does not touch an opponent. If the line does touch an opponent, the Black Mage then teleports to the opponent and attacks him with a series of quick combos with his staff and fists. This attack sends the opponent flying with the last blow, and Black Mage moves to the direction he was facing in a flash. This move is very useful for combos and combo finishers due to its powerful knockback. This is also a very useful attack in Team Battles since Black Mage can use Haste to finish the team member's combo. This move cancels all momentum when used out of hitstun. However, no horizontal distance is gained (unless if the attack connects with an opponent), making this move somewhat useful for recovery. It is widely considered to be one of the best edge-guarding moves in the game due to its huge range, accuracy, and overall distance it uses and the fact that it does not leave Black Mage helpless if the attack connects.

Wave Haste
Discovered and made by ZaloZemsis, Wave Haste is a technique that helps Black Mage create mindgames, have more range on Haste and help his approach. There is more than the earlier stated that help Black Mage.

To perform it, Black Mage must jump and when he gets very close to the ground, immediately use his forward aerial. This attack will give Black Mage a small pseudo-wavedash effect. Immediately after using the attack, the player has to use Haste. Black Mage should move while using Haste. If it connects, Black Mage and the opponent will be moving towards the ledge and the blow will push the opponent away from you. The attack deals 15% to the opponent.

Origin
In Final Fantasy games, Haste serves to increase the speed of an ally, increasing the number of times is ally can attack. In Final Fantasy I and II is a black magic spell, in Final Fantasy III and IV is a white magic spell, in Final Fantasy V it becomes a Time magic spell (called Time Materia in Final Fantasy VII) and in Final Fantasy VI is a type of Grey Magic.

Trivia
In v0.8a, Wave Haste was impossible to do, but in v0.9 it's now possible to do again.