How do I activate the soul cube?

[medfab]

I just got the soul cube- it says "use us" ...but I don't know how to activate it..can anyone help?

[Manc]

When it says that, it's useable. You can then shoot it like any other weapon, but after that you have to kill 5 creatures of any variety to get enough juice to use it again.

[Ichor]

And to bring it up, press Q.

[medfab]

Thanx for helping me! I can use it now!