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

[Zardnaar]

As the title says. If you were to design a PC killer monster how would you do it without going to over the top?

My theory.

"Unbidden" aka energy wraith

Flies
Immune radiant
Immune or resistant to elemental damage
Decent AC (18+)
Deal psychic damage/targets intelligence saves.

Extra dimensional energy being.

Anyone got any other ideas?

 

[Reynard]

I gotta go with the ultimate classic: the rust monster.

 

[Snarf Zagyg]

Nilbog.

 

[Medic]

The tools for designing an anti-player encounter come prepackaged with the game. Lead your PCs into a small enclosed space, preferably a room with a high ceiling or a pit of some sort, and find a way to physically block off any exits. Station a beholder above them that keeps its antimagic cone on them at all times. The spellcasters won't have access to any magic, and the martials' weapons will have their magic nullified.

Place an iron golem in the same room. Unless the players obtained adamantine weapons at some point prior to the encounter, the golem is, for all intents and purposes, totally invincible, as the characters have neither the weapons nor the spells to deal any damage to it. At best, the characters can plink away at the beholder with mundane ranged weapons, assuming the golem doesn't reduce them to ruddy paste first.

 

[CleverNickName]

An Abjuration wizard with the Lucky feat + his latest creation: an iron golem.

 

[MGibster]

Nilbog.

Not many people know this, but nilbog is actually goblin backwards. Shhhhh.

 

[payn]

Not many people know this, but nilbog is actually goblin backwards. Shhhhh.

WHAT!?

 

[Oofta]

So, so many ways. The beholder is a good idea. Another option is flame skulls. They're only a CR 4 and they're tiny. Have them cast blur on themselves before combat, sneak up on the group to within 150 feet and fireball everyone. Then just have them fly into tiny cracks in the wall or simply behind cover so the PCs can't respond. Remember, even if you kill them they come back after an hour unless you cast dispel magic, remove curse or sprinkle holy water on them so they'll be good to repeat the fireball fun the next day.

Not that I accidentally did that once - well I didn't have them hide after casting multiple fireballs.

 

[CleverNickName]

Not many people know this, but nilbog is actually goblin backwards. Shhhhh.

Once when I was a small boy, my mom told me that her name was "mom spelled backwards." She whispered this information to me, too, all serious-like, as if she was sharing a piece of forbidden knowledge.

Almost 50 years later and I still laugh about it.

 

[Eltab]

If your group is spellcaster-heavy, a beholder will do the trick. Turn on the antimagic field, stay at least 15 feet up, and eye-ray the archer first.