D&D 5E Worst Metagame Anti Player Creature Design?

[Imaculata]

In 3.5 there were monsters with a special ability to reroll a die, or to force the players to reroll.

 

[Zardnaar]

Horde of CR 1/2 Shadows.

Well they're well known for being a low CR PC killer along with Flameskulls and Intellect Devourer.

 

[Mezuka]

Hundreds of Stirges, wave after wave after wave.

 

[humble minion]

I recently read a 3pp adventure that had a flying CR 1/8 creature which inflicted a level of exhaustion (Cons save DC 16 to negate) along with its melee damage, and was encountered in groups of 4d4. I mean, you were not expected to encounter them til somewhere in the 5th-8th level range, but jeez, there's some serious death spiral potential there...

 

[James Gasik]

Let us not forget one of the classics, the vampire. If you face one without realizing what you're up against, it can be impossible to defeat.

 

[Mannahnin]

Well they're well known for being a low CR PC killer along with Flameskulls and Intellect Devourer.

The successors to Ghouls in old school (who notoriously punch above their weight, with three attacks causing paralysis per round).

 

[Dausuul]

Hundreds of Stirges, wave after wave after wave.

If you're gonna use this one, you have to provide the PC with an electric guitar and give them a chance to shred "Master of Puppets" first.

 

[tetrasodium]

Sul Khatesh in RFtLW deserves to be mentioned but raises an important question of what level players & what CR are you aiming at? An ogre can be a player killer if the players are level 1 but it's very much not if they are level 10

 

[Dausuul]

The successors to Ghouls in old school (who notoriously punch above their weight, with three attacks causing paralysis per round).

Even in 5E, they're bad news. The one time I've had my PC die to monsters in 5E, it was at the claws of a ghoul pack.

The DC may be low on that Con save, but you only have to fail one.

 

[Mezuka]

Always liked the Ghoul + Carrion Crawler combo.