A wraith will spawn in to your left, then an archvile round to the right and some cherubs behind you.
Turn left at the end and kill another wraith, then head right and grab the medkit on the desk. Turn round and find armor in an alcove on your right then some trites will attack. Get into the lift and choose level 3, Routing. There’s an imp to your left and cherubs to the right.
Go round to your right and kill a commando and then an imp to your left. Grab the ammo from the office on the left and go through the next door. As you walk in alcoves will open either side of you to reveal two imps and then a commando runs in. Grab the pick ups in the room off to your right and kill the two imps that spawn in, then kill a cherub and head up the corridor.
Take the door at the end on the right, kill another imp and grab the items from the open cabinet. Use code 468 to open the other cabinet, kill the trites and imps then an archvile and some cherubs.