Dead Horse Interchange

It's a very late cave mission, the first to introduce the small underground teleportation devices (a throwback to the old ant hills that EDF 5 has otherwise replaced with teleporter beacons). It is entirely set in what has to be EDF's most annoying cave level. The entire thing is centered around a giant pillar, with various paths leading up and down.
All the teleportation devices are in the upper third of the level, and your squad also starts there. Pretty much all enemy drops will fall down to the ground because the paths are so narrow, so you better hope they don't hit you too often.
And don't fall down if you can avoid it, or else you will have to find a way up as enemies keep respawning from above.