Help find the best icon/sound for a couple things.

I need a good hero ability icon for stimpack. Right now, I am using curse. Let me know if you can think of a better one.

I need a good icon for a Cloak skill. Invisibility would be ideal, but it is a skill you can turn on and off. Therefore, it needs to have a good activate and deactivate icon.

Lastly, what would be the best sound set for the marine?