Well you could use a nuke, but only if the nuke buff looks like its falling down, like star fall is. If you have a model like this, a falling nuke I mean, Ill tell you what to do...
I think you can change the starfall model to an imported nuke model (you'll have to find this urself) in the object editor by either:
1. Replacing all the starfall target, special and attachment models in the starfall ability (If there are any I can't remember.)
OR
2. Creating a new effect and using ur nuke model as the model file for the effect, then editing the starfall ability to use this effect in the 'Stats - Effect' field.
Keep in mind only one of these techniques will work, I'm just not sure which. It really all depends on whether the starfall ability uses the starfall model file as an attachment which can be seen when editing the ability itself or as an effect (meaning that the starfall model is being used in an effect and this effect is being used with the starfall ability).
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.