Magma Barracks

Spawns
Evolved Lemurian

Wisp

Bighorn Bison

Mechanical Spider

Bosses
The Direseeker

Cremator

Toxic Beast

Scavenger

Artifact
The artifact gate appears at the far left, on the middle level. The artifact is triggered by activating the three switches located in the level (example on the right). The switches are activated by shooting them, but as they are behind walls it's necessary to use an attack that can reach through the wall. Confirmed way to press switches : Bandit's Dynamite, Huntress's Cluster Bomb, Enforcer's Shotgun, HAN-D's FORCED_REASSEMBLY, Acrid's Festering wounds, Miner's To The Stars. The Cremator's artillery shots will also activate the buttons.

Two of the switches are located in the open at upper left and center of the level, while the third is hidden partway down the left-most narrow shaft and requires a little timing to activate. Note that the switches appear on the map variant that does not have lava at the bottom of that area (i.e. not Variant 1 depicted below).

Once all three switches are activated the artifact Sacrifice will appear on the gate.