Diablo 4 regularly tries to present a challenge to players throughout the majority of the campaign. However, once you get to the higher levels you might start to think things are getting too easy. So, there's a simple solution: you challenge the Capstone Dungeon and move up a World Tier.
Except, eventually, things will start getting too easy again, and while one-shotting things is fun, sometimes you want a genuine challenge through a difficult World Event or dungeon. Nightmare Dungeons are the definitive answers to your calls and they come in a whole variety of challenges, from Tier One Nightmare Dungeons (the easiest ones) all the way up to Tier 100.
10 Capstone Dungeons
Capstone Dungeons are the easiest ones on this list for the sole reason that you're probably prepared to go into them. If you want to head to World Tier Three or World Tier Four, you will need to complete each world's respective capstone dungeon. The first Capstone Dungeon, Cathedral of Light, requires that you finish the main campaign and that you're level 45-50.
The Sacred Physician in this dungeon will regularly revive the other bosses if you don't kill them first, so keep your priorities in order. The second Capstone Dungeon is in World Tier Three and is called the Fallen Temple. If you want to take this one on you should probably be level 65-70. The lower your level, the harder it will be. To beat this Capstone, you'll have to beat a significantly difficult boss, Elias, Hatred's Remnant.
9 Shivta Ruins
Flies are some of the most annoying enemies in the entirety of Diablo 4. They're small, hard to see, and you sometimes don't even realize that they're on top of you until you're slowed, so if you hate them the Shivta Ruins is the perfect dungeon for you because they are found in an absolute plethora here.
These nightmarish little enemies, combined with a Nightmare Sigil, make the dungeon an actual Nightmare. It's even worse if the flies have increased health, which makes you have to spend too much time on this one, tiny enemy.
8 Maugan’s Works
Maugan's Works is difficult specifically because of this Dungeon's final boss, the Knight Council. If you've done the first Capstone Dungeon in World Tier Two then you've likely run into this group before (or at least, a similar one). The Knight's Council is composed of a Sacred Physician, Grand Inquisitor, and Lord Commander.
The Lord Commander is pretty much your standard fighting boss, but the Grand Inquisitor and the Sacred Physician are exceedingly annoying as the former will regularly try to blind you and teleport and the latter will revive the others if it is not downed first. Use a Nightmare Sigil and you're in for a wonderfully challenging experience.
7 Champion’s Demise
The Champion's Demise dungeon can end up being pretty annoying to work your way through because not only there are a lot of enemies (as per usual), but those enemies can do a lot of stuns, and the high-damage enemies nearby can take advantage of that. You can't heal when you're stunned, which means you're just forced to watch your health drain, especially if you're just getting stunned over and over again.
The streak of being stunned and watching your health be sapped away doesn't end as soon as you reach the boss because this one, Kahzra, Abomination, can do it too. Have fun on the Nightmare difficulties because you're in for a frustrating time.
6 Ferals' Den
Ferals' Den requires you to hunt down Animus Carriers and deposit them in the Animus Urn if you want to access the main boss. Of course, this tends to make the dungeon fairly annoying and guarantees you'll run into lots of enemies.
This problem can be exacerbated because Ferals' Den has a fairly high chance for the Animus carriers to be grouped up, which means you can be dealing with swarms of standard enemies on top of two elites that can have a range of incredibly frustrating abilities (poisoning, freezing, and summoning tend to be the worst).
5 Vizjerei Athenaeum
The Vizjerei Athenaeum is part of the Izel of Vizjerei quest line and for the most part, this series of tasks is perfectly fine and do-able. At least, until you get to the final part. After interacting with the altar, Izel will arrive and suddenly become determined to kill you, which is fine - most side quests tend to lead to this point.
However, Izel's attacks are exceedingly annoying, which makes her dungeon pretty tough, especially on higher World Tiers. She can make you vulnerable and then execute a high-damage attack which, if you're not prepared or on top of your health, will one-shot you.
4 Witchwater
There are so many Nangari Oracles in the Witchwater dungeon, which means your chances of being stunned for a long time are exceedingly high. If you have abilities that can cancel stun or your control impairing effect time has been decreased, you'll probably be okay.
However, for those of you who don't have that benefit, you should probably bring a friend to help you out here. On higher difficulties, you can only help but watch as you get stunned over and over again and take hits from incredibly strong enemies so quickly you'll run out of potions before you can blink.
3 Most Negative Affix Nightmare Dungeons
Although Nightmare Dungeons can give you a positive affix that will increase the amount of experience, gold, or otherwise that you can earn from a Dungeon, there are a handful of negative affixes that will only make your life harder. Affixes like Backstabber will allow enemies to deal deadly amounts of damage to you if you're hit from behind, which is especially frustrating if you end up in a Dungeon where you are swarmed often.
Armor-Breaker is just as bad because it essentially makes that super-high armor stat you've spent forever grinding for practically useless. Of course, not all negative affixes are horrible because they can generally be subverted by being careful or taking your time, such as Potion-Breaker.
2 Mahjoob's Safehouse
Mahjoob's Safehouse contains one of the hardest fights and toughest "bosses" in the game (and Mahjoob isn't even technically a boss). On higher World Tiers (Three and Four), this fight is practically impossible, so don't feel bad if you need to go to World Tier One to beat it.
The rewards won't be as nice, but at least you managed to beat him, right? Mahjoob's life-steal ability is the bane of existence, but it can, thankfully, be interrupted with attacks that stun or temporarily incapacitate him.
1 Torment Dungeons AKA Tier 100 Nightmare Dungeons
Do you want a serious challenge that will put all of your skills and your entire build to the test? Hop onto World Tier Four with a Tier 100 Nightmare Sigil you've crafted. It doesn't particularly matter which dungeon you choose, considering that you will likely die so many times anyway that you might not even be able to complete it.
Nevertheless, once you've accessed your Nightmare Dungeon of choice prepare for it to become the hardest experience in Diablo 4 you've ever had. These dungeons are painful and will ensure that you experience the word "pain" in its truest, most horrifying form. However, this is one of the few things that you should spend your gold to try out.