For Carnage Apply Within is the sixteenth level of Marathon 2: Durandal and the third of the Durandal chapter. In this level, you need to make your way to the exit terminal while fighting through hordes of S'pht Compilers and Pfhor Enforcers. The map is quite open and it features a lot of platforming gameplay as you jump between different platforms in a plasma-flooded environment.
The only pattern buffer on this level is at the very south end, next to a 2x shield recharger.
Right at the beginning of the level, be ready for some close quarters combat, as you'll encounter a "trap"; a number of walls will briefly drop down, putting you in a small area with a bunch of Enforcers teleporting in. Kill them and go through a door leading east. In the north side room, you'll find some ammo, including rockets, and a 2x shield canister.
Heading further east beyond the side room is dangerous, as you'll trigger a large ambush with tons of enemies appearing everywhere. It's safer to go south, into a large room flooded with plasma. There are many platforms and pillars here. The idea is to jump across from one platform to the next, making your way to the south end of the room where you'll find a pattern buffer and a 2x shield recharger.
Each time you jump to a new platform, a Compiler will spawn somewhere nearby. Be careful, their shots can knock you into the plasma. There are two strategies you can use: either take it slow, advancing one platform at a time and dealing with each Compiler as it spawns, or run across to the shield recharger as quick as you can and deal with the Compilers there as they approach you.
From the pattern buffer, make your way to the northeast corner of the level. The southbound corridor leads to the final room of the level, in the southeast corner; as you traverse this corridor, a large number of enemies will teleport in. Quickly run forward to either the final room (there are a couple of Enforcers inside) or to the pattern buffer platform and kill all the enemies.
In the final room, be sure to pick up the ammo there, and use a shield canister if you need to, before you read the exit terminal to go onward to Begging For Mercy Makes Me Angry!.
In the northwest corner of the large plasma-filled room, there's a pool of plasma with a bunch of ammo at the bottom. South of this pool you can climb on a platform with an elevator that leads to an Enforcer guarding more ammo.
This terminal is from Tycho. He rejoices in Durandal's destruction; he says it was Durandal's hubris that destroyed him. Tycho explains that Durandal thought the eleventh S'pht clan vanished (along with their moon) after they discovered an ancient Jjaro outpost, the Jjaro being a mysterious, technologically advanced race that disappeared millions of years ago.
This terminal contains two highly corrupted messages. The first one is completely unintelligible, but the second one contains a few lines from Durandal, who asks you to destroy his core logic centers so the Pfhor can't get their hands on him.
- You can skip most of the ambushes by rocket-jumping up to the last room from the area with the 2x shield recharger and pattern buffer. There are shield canisters in the last room so you'll only have to be careful for the two Enforcers there.