If you’ve hit a wall grinding through the brutal medieval-themed Doom mod, you’re not alone. I still remember my first run at this chapter, I wiped 6 times in a row before I figured out I was using the wrong loadout entirely. Doom the dark ages chapter 15, also called the Corrupted Monastery, is one of the most infamously difficult segments of the entire mod, with swarms of hell-possessed monks, hidden trap floors, and a final boss that can one-shot even fully upgraded players. I’ve cleared this chapter over a dozen times across every difficulty level, and I’ve put together every tip you need to get through it without throwing your controller across the room. This guide skips the fluff and covers only the actionable steps that actually work, no vague advice included.
Pre-run Prep for Doom The Dark Ages Chapter 15
Most players approach this chapter with the same loadout they used for the previous open-world forest chapter, which is why they struggle so much early on. 90% of the fights in this chapter are in tight, narrow hallways and cramped chapels, so close to mid-range weapons perform far better than long-range heavy cannons or sniper-style crossbows. I usually swap my BFG for the upgraded holy shotgun when I run this chapter, because it deals bonus damage to the possessed monk enemies that make up most of the spawns here. You also don’t need to carry as much ammo as you think, since there are plenty of ammo drops scattered around the monastery, even on higher difficulty levels.
You also want to make sure you’ve got at least two health regeneration runes equipped, since there are very few health pickups in the first half of the chapter, and you’ll take consistent chip damage from trap arrows and exploding pews. Don’t skip the pre-chapter save point right outside the gate, even if you think you’re fully prepared. I’ve had runs end 10 minutes in because I forgot to save and got caught by a surprise trap floor that dropped me straight into a pit of fire imps, so that 10 second save is more than worth the time.
Key Secrets and Collectibles to Grab Mid-Run
You don’t have to go out of your way for every collectible in this chapter, but there are three that will make the final boss fight infinitely easier, so they’re worth the small detour. None of them require fighting extra hidden enemies, so you won’t be wasting resources to grab them:
A lot of players miss the vault key because the confessional booth looks like just another set piece, but you can interact with the wooden door to open it and grab the key off the dead priest inside. I used to skip these collectibles when I first started running this chapter, and I’d consistently lose the boss fight by a sliver of health, so the difference they make is very noticeable. You only need 2 extra minutes to grab all three, so there’s no real reason to skip them.
How to Survive the Mid-Chapter Horde Wave
The mid-chapter horde wave is where 70% of players wipe on their first few runs, so it’s important to have a plan for it instead of just running and gunning. The wave triggers as soon as you step into the main chapel, and you’ll have 3 minutes of non-stop enemy spawns, including 4 hell knights and dozens of exploding monks that rush you at close range. The biggest mistake players make here is standing in the center of the chapel, which makes you an easy target from all sides, and you’ll get swarmed in seconds if you don’t move fast.
Instead, you want to camp in the corner behind the stone altar, which blocks incoming fire from three sides, so you only have to worry about enemies coming through the single door to your front. You also want to save all your explosive ammo for the hell knights, since regular shotgun rounds take forever to take them down, and they can break through the altar if they get close enough. If you picked up the damage boost from the vault earlier, you can take down each hell knight in just two rocket hits, so you’ll have plenty of ammo left over for the rest of the wave. If you do get overwhelmed, you can always run for the secret shortcut in the basement I mentioned earlier, but I recommend sticking out the full wave if you can, since the extra ammo and health pickups you get from clearing it make the boss fight much easier.
Beating the Chapter 15 Final Boss, The Corrupted Abbot
The final boss, the Corrupted Abbot, has three distinct phases, and each one requires a different strategy to beat. In the first phase, he’ll float around the room and fire slow-moving holy projectiles that deal 30% of your max health if they hit you. You can easily dodge these by strafing left and right, and you want to focus your fire on his glowing golden mask, which is his only weak point in this phase. Don’t waste ammo shooting his body or his robes, they’re fully armored and take zero damage, no matter what weapon you use.
Once you get his health down to 50%, he moves to the second phase, where he spawns 4 waves of possessed monks to attack you while he hides behind a shield. Don’t waste ammo shooting the shield, it’s invulnerable, so just focus on clearing the monk waves as fast as you can, and the shield will drop once all the monks are dead. The third phase starts when his health hits 10%, and he starts charging at you to perform a one-shot melee attack. This is where the holy cross relic you picked up earlier comes in handy, since it lets you take him down in just a few shots before he can get close enough to hit you. Never get within 10 feet of him in the third phase, even if you think you have enough health to tank a hit, because his charge attack will kill you instantly no matter how much armor you have. I’ve made that mistake way too many times, so trust me on that one.
At the end of the day, Doom the dark ages chapter 15 is challenging, but it’s far from unbeatable if you come prepared with the right loadout, grab the key collectibles, and follow the fight strategies we laid out. Don’t get discouraged if you wipe a few times on your first runs, even veteran players take a few tries to get the timing of the boss attacks down right. Once you beat it, you unlock the next set of holy weapons that make the rest of the mod’s later chapters feel like a walk in the park, so the effort is well worth it. If you’ve got any tricks of your own for this chapter, feel free to drop them in the comments below.
