Monsters that punch above their CR

[Retreater]

Hellhounds. I TPK'ed a group with their breath weapon attack.

 

[Ralif Redhammer]

Ghosts are pretty terrifying, absolutely. Heck, even if a PC survives their aging, some character concepts just don’t handle going to elderly all that well, and can be just as much a death knell, as, well, death.

Ghosts' Horrifying Visage can seriously reduce a character's life expectancy if they fail their save and are unlucky on the d4 roll. An extra 40 years of age if you're playing a human or half-orc who's already at the 'grizzled veteran' end of the spectrum will put you well into the pensioner bracket - permanently if you're more than 24 hours away from a spellcaster capable of casting greater restoration. Multiple ghosts in short succession could easily be fatal, and since it's technically death due to extreme old age, you're out of luck for resurrection at any level.

 

[neobolts]

Flying Snakes - 1/8 CR. Only 5 hp, but AC 14, 60ft fly speed with Flyby ability. +6 to hit doing 1 piercing plus 7 poison. Against a swarm of them, if you don't have AoE damage (or poison resistance), you will die.

I came looking for this. Flying Snake swarms will destroy a 1st level party. I have a party of PCs that still talk about the snakes in hushed tones at level 11, lest they appear without warning.

 

[Luz]

In my experience, ropers are horrendous things to fight at any level. A calculated "Easy" or "Medium" encounter with ropers is never that. High AC, reach, and plenty of attacks make these guys extremely dangerous and hard to put down. With a bite that inflicts 4d8+4 damage, god help anyone who is on the receiving end of a critical hit. That said, I love ropers.

By extension, MToF has a new monster called the Lonely (under the Sorrowsworn entry) that has a similar attack routine with enormous reach. Granted, they are CR9 but these baddies are nasty with an excellent damage resistance and inflict continuous psychic damage. I sicked a couple of them on a 14th level party recently and it took the party everything they had to defeat them.

 

[Azzy]

From Fifth Edition Foes, the Giant Slug of P’nakh. CR 4, but two of them (with two Astral Sharks) were a handy challenge for five 13th-level characters. Nearly killed the rogue, and my sorcerer was out of commision for most of the combat.

 

[77IM]

The solar can't heal itself, it can only heal "another creature."

 

[Plamodu978]

I Think Thorny is can make bored battle,If party does not have a information about Thorny, he cannot die.

Thorny (1 CR, VGM)

Regeneration. The thorny regains 5 hit points at the start of its turn. If it takes cold, fire, or necrotic damage, this trait doesn't function at the start of the thorny's next turn. The thorny dies only if it starts its turn with 0 hit points and doesn't regenerat

 

[Ralif Redhammer]

The CRs in Fifth Edition Foes, are, in general, a little off. The Demonic Knight is another one from there that hits harder than the CR would indicate.

From Fifth Edition Foes, the Giant Slug of P’nakh. CR 4, but two of them (with two Astral Sharks) were a handy challenge for five 13th-level characters. Nearly killed the rogue, and my sorcerer was out of commision for most of the combat.

 

[TaranTheWanderer]

LOL. So ponies usurp the domestic cat as the unforseen bane of low-level character in this edition.

I don’t remember the edition but I remember swans being very, very scary.

 

[Ralif Redhammer]

Pretty sure that the edition is "real life." Swans are mean birds.

I don’t remember the edition but I remember swans being very, very scary.