"Put some hustle in even your heaviest units! Haste Spells lack the damage boost of Rage Spells, but provide an even better boost to movement speed. A lower storage space also allows you to take more of them into battle!"

Summary 
The Haste Spell is a Dark Elixir Spell added in the July 1, 2015 update. Like a Rage Spell, it boosts the speed of troops in its area of effect; the Haste Spell, however, does not make them deal extra damage. The Haste Spell has a slightly smaller radius than a Rage Spell.

Offensive Strategy
 Haste Spells may be used to counteract the effect of Air Sweepers. The Haste spell is most effective in aiding slower but more powerful troops, such as Balloons, Dragons and P.E.K.K.As. Before the July 2015 Update, Balloons were combined with Rage Spells to increase their speed. When the Haste Spell was introduced, Lavaloonion, LaLoon, Balloonion and other variations saw new light due to the larger speed increase and consuming half the housing space of a Rage Spell.

Trivia 
The Rage Spell's name in game files is haste. A level 1 Haste Spell has the same speed increase as a level 5 Rage Spell, its maximum level. For every 1 level the Haste Spell gains, the amount of speed it gains is always increased by 6.