How do I get Mortar Impact Effect?

My original plan was to make a unit based off the mortar missile and kill them when i needed the effect. The problem is it goes off way too fast and unit death speed doesn't alter it at all. So my question is what is the best way to do this? I need a re-sized slowed down mortar impact effect.

No one has any idea? It would really help the effect I am trying to accomplish.

what do u need this affect for?

I have a marine hero class who's ultimate is nuklear launch. Mortar Impact looks just like a nuke. It's a multiplayer game and once the marine hits 6, he will be expected to cast it a bunch of times per games so I don't want to have anything ultra fancy. I'm just using flamestrike/mortar impact/terrain ripples. it'll be perfect if the animation is slowed.

EDIT : spelling

this is exactly like my map. I have a nuke at lvl 6 for marines and firebats. Abilities\Weapons\Mortar\MortarMissile.mdl its the missile but the missiles death animation is that nuke effect.