Halo 2 ultimate weapon : FPS / MMORPG / RTS Discussion

This is easiest done with Co-op

You start this lvl regularly except kill EVERYTHING including your own people. head across the bridge in the tank there will be a bunch of ghosts and a few banshees and some wraiths. Destroy them all then when u get to the end Cortana will say "Well that was quite a welcoming committee" then out come 3 banshee's and 2 ghosts, destroy all of them. then out come 2 more banshees and 2 wraiths destroy the 2 wraiths and 1 of the banshees. If your in Co-op have one person kill everything in the tunnel and another outside detracting the banshee. when u come to the end u'll find a little room with a jackal, kill the jackal but don't enter the room. Come back out and help player 2 get the banshee into the tunnel after that just lead the banshee through the tunnel and once u reach the circular room both hit x or the banshee with disappear. so now just fly outside and strait up if u see bridges fly to one of them look around until u find a plasma rifle then pick it up and u got your weapon

Whats the plasma rifle do? Is there something special about it?