Act 2: Nightfall - 9. Alamo

This is not that tough. If you have some Frags, just lob them in the hole up ahead. If not, there are a few if you go to the otherside of the catwalk. Try your best to close all three up ASAP. You may note the tiny lights in the buildings in front of you, ignore them. But do get on the Troika and aim for the concrete slab across the way, above some dude.

Soon after a Boomer shows up, so fill him with Troika bullets. Mow down all the other Drones and Grenadiers; use your Lancer and remaining Frags in need be.

When all seems clear collect the gear and turn around. Wait for the huge hole with four Boomers to open up. Don't bother with killing them the old fashion way. Notice the big water tank that will eventually drop to the left. Keep waiting and avoiding the boomshots. When you see a panel drop under the tank, you will see three propane tanks; shoot them and you defended the Alamo, now wait for the boss, Ozzy the Streamer (joke, for those out of the know).