Leashing ability help!

I'm trying to make an ability so that when you target a unit, that unit can't move and gets pulled towards the caster. They can't go out of range of the caster for 30 seconds. I have no idea how to get the area to work for just one unit, though.

Do you mean that the caster channels the spell and while he channels it, the target unit is immobile and slowly moving towards the caster? Or do you mean that when the ability is cast, the target unit becomes bound to the caster and may move at will, as long as it isn't getting out of range of the caster?

In any event, storing the targeted unit to a variable and then operating with that variable allows you to make it work for only one unit.

that one

The problem is, I dunno how to detect if a unit is in range of the caster and move it if it's not in range.

Real - Math - Distance Between points

Okay, I got it to work now but I want to add a chain effect to it between the caster and the target. but every time I move to chain caster to the position of the caster, it stops channeling the chain spell.

you might try to use the drain ability for base ability or finger of death with a high graphic duration

Would the Finger of Death graphic duration work if the caster is moving?

yes, unless you remove the finger of death ability