I wander what do you do in DoomII level 30: Icon of Sin

If you know please give me adwise.

well, after you get all of the weapons, pass through the portal, and hear the backwards voice of John Romero you should start making your way up. Keep going up until you get to the top. There should be a switch there that you can push. Quickly turn around and run down the stairs until you get to the 1st part. Try to run on the raising platform. If you get on it, when its rising, equip your rocket launcher. Face the big demon looking thing on the wall. When you get to the brain part, pump out rockets like thers no tomorrow. Keep doing this untill he explodes.

An easier way of doing this is to get a port that supports mouselook. If your using one, then get to the top level, aim for the exposed brain and fire several rockets.

I hope that answers your question...

isnt this DOOM
no doom 2 is here... me dont smell none.
Haha... that was awesome!