Spell Help: Frost Jet

I want to give one of the heroes in a map I'm working on an ability called Frost Jet.

It's a channeling spell that can be cast on a unit or the ground. The caster forms a stream of frost that extends a certain distance in front of him. Any foe that steps into this stream is slowed down by cold and takes a certain amount of damage per second. As the level increases, the range and damage per second of this skill is increased.

I was thinking of basing it off of Shockwave, but I need the spell to do damage over a period of time instead of a single hit. I could also possability base it off of Tornado somehow. Any ideas?

Hows about earthquake with a low AoE, then changing the final area?

EDIT*

Spectre's way is good. :)

Flame strike deals damage over time if the unit is under drunken haze. Parhaps you could use that.

Yes,
dyne has got a good idea there, btw you mean breath of fire. You cannot bas eit off earthquake btw, becuase that only effects buildings :bgrun:

Hmm... doing a spell like that is hard you would have to actually have to do the old way of spell editing if you chose to do a spell like that, with microsoft excel and the mpq extractor ect...

BUT

You could base it off tornado and change the model file for tornado [as it is a summon] to a frosty spell effect like breath of frost, just change the model file of tornado to a spell projectile and maybe stop its movement or what have you, it best just to experiment with it until you find out what fits best to your type of spell. GL:D

well i would take and make a unit which had endurance aura and then order the unit to move with an offset....