I was able to change the Warp Prism's model height since when I changed it to a ground unit, the model kept being halfway into the ground. I forgot exactly how but it was a simple 'height' modifier change either in the actor or in the unit. Wezthal's image is probably it.
Whatever you do, do NOT use a trigger. It is easier to do so but it is wrong and more triggers will mean more lag/junk.
Bad Warcraft 3 modders were those whose maps had leaks. The equivalent for Starcraft 2 will be people using triggers for things that can be done in the Unit Editor.