yeah if u want to get rid of cast time, use berserk
This just goes to show how much berserk owns sh*t up... LOL
Seriously though, doom_sheep makes a good point, no casting time (I forgot to mention that in the above post). It can be used as a "burst of speed" (attack or movement) kind a spell, which sounds like what you're after. You don't need any triggers or dummies to do the dirty work, you can just use the game engine.
Tip: Use a custom buff (EG: berserk based, called "Burst of Speed"), in the effects list, put the Buff/Cripple art, in the various attachment entries put (i'll use ; to seperate this list): head; chest; hand,left; hand,right; foot,left; foot,right. Then set the number of attachments to 6. Using this "trick" will make the effected unit/s leave a pretty cool looking red trail behind them when they move, this also applies to their arms when they attack. Trust me, it adds a nice element, I'm one for creating basic eye-candy with Wc3 abilities.
Hope this leads you well.