As everyone else already said,

PB Blaster
Heat
Screwdriver and rubber mallet

 

actually heating up the collar sounds like a good idea.
i have a heat gun. would it be fine to heat up the collar and everything around it, like the bottom shock and the strut w threads?
i dont think i can be so accurate that i can only heat up the collar.

 

No, dont use a heat gun, Use an actual torch and heat up all around the collar. Keep the flame away from the bottom mount.

 

then the coilover needs to be off the car. its going to be a PItA to break it loose when its off the car. even its mounted on the vice.
i have a feeling the bottom piece is going to bend or something if vice is used

 

I would think twice before I used a torch on a High Pressure gas strut

 

it should only take about 10-20 seconds of heating the collar. as long as you dont focus the heat on the body it should be fine.

 

Just hit it with your purse

 

Aluminum heats up how fast

 

very fast...the body should be steel or stainless. if your afraid of heat dont use it, but its a very useful tool for stubborn nuts, bolts etc.