You're right. The Xtreme is the most powerful move within the character's arsenal of powers which define them as a Marvel Super Hero.
As I've pointed out about my broken-down mongrel of a computer almost everytime, I cannot install MUA on my laptop as it takes up too much space in my hard drive. Plus, my graphics card isn't that strong, and the most I can see is shadows, but I've learnt to fight using shadows, technically dueling invisible opponents and using the useful aid of the GameFAQ's walkthrough that you provided me in the "Which DLC Character would you most likely try?" thread.
I noticed that you said that you had a problem seeing graphics on MUA. I had this problem as well but found that 3d -Analyze may fix this. It fixed mine.
You can find it by googling "3d analyze" and clicking the first link (it should take you to some site in Italian)--the site: http://www.3dfxzone.it/dir/tools/3d_analyze/
Download the latest version or whichever
After installing it and whatnot, enter the settings below and click run. Do not run the MUA game directly. The program should run the game for you (upon selecting it of course).
Hardware Limits (cap bits)
* emulate HW TnL caps
* emulate pixel shader caps
* disable lighting
It should work pretty well then, running slowly only in part of the Skrull world and that is in only part of that Skrull world (it doens't impede gameplay as much).
Sidenote: The Mysterio mod rocks.