It might be hard to believe, but at one time Act V of Diablo 2 had twenty-five special unique monsters on it. After deciding that was a bit too much overkill, five were removed. Even at twenty, this is still about double the number of fights from the average of Acts I-IV. Players always want their money's worth when it comes to extra content. That extra content was delivered in spades for the expansion, taking the form of both thrilling battles and raw pain.
The worst-ranked sub-bosses shouldn't be confused for an Act I elite mob. Blizzard was well aware that players at this stage likely had every piece of gear they could possibly want and every skill point masterfully invested. So they adjusted these fights accordingly, assuming that players believed they would be prepared. This expansion proved to the community that the toughest challenges were still to come.
20 Thresh Socket
Everybody from the rough and tumble barbarian to the nimble and precise Amazon can use additional gear. Thresh Socket has a big chest strapped to his back and makes for an obvious target. Indeed, this was a super unique monster that appears best suited for farming and doesn't pose a real threat.
19 Pindleskin
The druid in Diablo 2 may or may not be worse than the druid in Diablo 4, but even the weakest of druids at this stage in the game knows how to handle a zombie. Pindleskin's fire enchant is really only helpful if he can get a few hits in, but he's just too slow to make that happen.
18 Dac Farren
Much like Pindleskin, Dac Farren's Cold Enchanted bonus only matters if he can connect with his blows. Classes like the druid take time to understand, but Dac Farren will likely not pose a threat regardless of how badly built the given character is.
17 Madawc
As one of three guardians, Madawc is embarrassingly worse than her counterparts. She throws hatchets which deal very little damage, even to lightly armored players. There are games to play to pass the time until Diablo 2: Resurrected comes out. Play those games to bide time instead because this fight will be over for poor Madawc in just a few seconds.
16 Eldritch The Rectifier
Poor Eldritch is probably the most killed monster in the game. He's close to a waypoint and drops great gear, so it's common for parties to kill him on repeat. Plus he's so easy that players who choose their class based on their zodiac sign will be able to easily dispatch him.
15 Snapchip Shatter
So long as the character can do any kind of damage besides cold, Snapchip Shatter doesn't really inspire terror in anyone. There are a few excellent mods for Diablo 2 that can beef this monster up, but as far as the base game goes, he's a one-trick pony.
14 Sharptooth Slayer
The Sharptooth Slayer is fast and that can be deadly when combined with another bonus on Hell difficulty. On the normal settings, he'll get his licks in but he doesn't have the power to his punch to pose a real threat. Maybe his other bonus was part of the game's cut content.
13 Frozenstein
Some super uniques were designed with one and only one character in mind. The ice-spellcaster sorceress will be in a lot of trouble when coming across Frozenstein. Everybody else will have a good chuckle at her expense and then breeze through this battle.
12 Eyeback The Unleashed
Extra Strong and Extra Fast bonuses stack nicely together and so this fight is when the real challenges start to kick in. On the standard difficulty, a little armor and some burst damage can toast him, but higher difficulty settings require careful thought on how to approach him.
11 Bonesaw Breaker
Usually skeletons, even special unique skeletons, are to be laughed at and destroyed. But Bonesaw Breaker and his minions all come with a special charge attack that makes them a ranged and lightly-armored character's supreme annoyance.