Begging For Mercy Makes Me Angry! is the seventeenth level in Marathon 2: Durandal and the fourth level in the chapter Durandal. It takes place in Durandal's core computer room and the surrounding areas. The objective is to destroy all eight of Durandal's circuit panels, so the Pfhor can't capture him.
At the end of the first side room there's a 3x shield recharger. A pattern buffer can be found in the second room. There is a 2x shield recharger at the end of the fifth side room, and another pattern buffer is located in the seventh room.
You'll start this level off in Durandal's central computer core room. There's a lot of ammo here, but also many groups of enemies that teleport in when you walk through certain parts of the room. Slowly make your way around the room, clearing each group of enemy as it appears.
The path through the rest of the level is very linear. There are eight side rooms accessible from the core room; these rooms are initially closed, and will open up one at at time. Each time, you'll have to visit the newly-opened side room, hit a switch at the far end, return to the core room, and destroy a circuit panel to open the next side room.
You'll find a 3x shield recharger at the end of the first side room, next to the switch you need to hit.
The second room has a little teleporter maze; take the teleporter north of the entrance to find a pattern buffer, and the teleporter north of the buffer to get back to the entrance. The switch is just across from the pattern buffer.
On the east side of the third room, you'll find a button just above a plasma pool. It raises the platform in front of it; jump to that platform, and you'll find another switch to hit to your northwest.
The fourth button is found in a small, plasma-filled room (map location A1). Jump on the platform in the room; it will drop down into the plasma. Behind it, on the north wall, is the button you need to hit to proceed further into the level. The door will close when you enter the room; a submerged button to the left of the door reopens it.
Once you destroy the fourth circuit panel in the central room, the 3x shield recharger will be disabled.
You'll find a 2x shield recharger at the end of the fifth side room, next to the button.
The sixth side room is identical to the fourth room; hit the north button behind the elevator platform in the small plasma-filled room (map location A2), then hit the button left of the door to get out.
After destroying the sixth core circuit, the pattern buffer you found earlier will be disabled. Fortunately, there is another pattern buffer in the seventh room. The button in that room is found in the pool north of the pattern buffer.
The eighth and final side room is another teleporter maze. Use the center south teleporter to get to the button, and the teleporter just south of the button to get back to the first room. Go back to the core computer room, and destroy the final circuit to be immediately teleported to the next level, The Big House.
This terminal contains a message from Tycho. He asks you to lay down your weapons to be granted amnesty, and warns you that things are going to go very badly for you if you continue. Additionally, he reveals that Durandal is being downloaded to a Pfhor containment unit designed by Tycho.
Marathon 2: Durandal - Level 17: Begging For Mercy Makes Me Angry