How would I do this?

Hold on, I'll edit this with the answer, just need to copy/paste, alright?

EDIT: Alright, I couldn't find it, so I'll just type it out.

Basically, It's on Avalanche, near the shotgun keyhole. You look at the shotgun spawn, spin around, and start walking towards the man cannon. Notice where the floor turns to glass (brown to black)? the black floor is where you take the shots. Put weapons, equipment, even people on the floor, then add something to look through, like a Regen, Power drainer custom powerup, or a Spartan Laser shot, to add the color. Be sure to look at the floor from inside the cave, if you're too close to the shotty brown area, the effect disappears.'

If you need more help, you can PM me.

 

if yous talking about the yellow, im guessing a sentenial beam if not read ^^^his^^^

 

Did you get something like it? I would try adding something in to colour it, like Theorem said "Spartan laser, or power drain". Just try something that explodes to give it a yellow tint.

 

Ok, I KNOW that's a Sentinel Beam in the example. You just need to shoot the laser over the glassy section on the floor where you laid out the weapons. Get really close to the beam and then look towards where you shot it, like down the beam itself, but still have those tiles in the pic.