Custom JASS Triggers

Could anyone do me a favor and make a custom trigger to do something to a unit, I mean, you have move instantly, order to attack, remove buffs, etc. But, you can't put a spell on a target unit without creating a unit first. If anyone can make a custom trigger to just spell a unit, tell me, I apreciate it.

Well you can't cast spells with triggers. The best way to simulate it is to create a unit, hide it, and order it to cast the spell. Yes, hidden units can cast spells.
Don't forget to remove them again.

Hm... Ty, I Apreciate It, Anyways, Can You Make Me A Model That Is EXACTLY Like A Cityscape Tree And Modify Its Class To A Unit? Whenever I Make A Unit With A Destructible Model, It Crashes The Game... =).

It depends on what you want the spell to do, but you could use a special effect to simulate the spell annimation then add damage and stuff after using other triggers.