D&D 5E Looking for monsters to challenge a party of 6 level 17 characters

[Paul Farquhar]

Running out of MM options! On the upside the players aint that tactically brilliant.

At the moment I really need a non-boss not-smart single monster of large or huge size.

 

[Lyxen]

The simplest thing to do is to create a legendary version of a standard monster. Take a Gorgon, triple or quadruple its hit dice, add a few points to its attacks and saves, etc. and have a look here.

 

[Paul Farquhar]

The simplest thing to do is to create a legendary version of a standard monster. Take a Gorgon, triple or quadruple its hit dice, add a few points to its attacks and saves, etc. and have a look here.

Yeah, done a bit of that (the boss is a legendary-ed Death Knight). There aren't many non-unique standard monsters even near the correct CR though (around 23). Not every fight can be against an archdevil or demon prince!

 

[Lyxen]

Yeah, done a bit of that (the boss is a legendary-ed Death Knight). There aren't many non-unique standard monsters even near the correct CR though (around 23). Not every fight can be against an archdevil or demon prince!

I agree, but remember that in 5e, due to bounded accuracy, action economy is king, and that multiplying monsters is an extremely effective way of adding threat to an encounter.

 

[Jfdlsjfd]

Yeah, done a bit of that (the boss is a legendary-ed Death Knight). There aren't many non-unique standard monsters even near the correct CR though (around 23). Not every fight can be against an archdevil or demon prince!

Surprise the players. A single monster is often not a match for a group because of action economy... so have

a) reinforcements
b) a tiered monster.

Sure, you can't fight an archdevil each time, but have a lowly reskinned Iron Golem as a cultist, covered in unholy protective symbols... When he is at half HP and the players says "sure, an easy fight" have him sound an horn and summon a few beefed up hell hounds (reskinned young adult red dragons) and recovers from detrimental effect and heals. And when killed, when the players are all doing hand checks when you say "he falls... imploring his dark lord to take his soul completely" and his body transforms (explodes...) into a goristro. You'll see the players be extremely stingy with their remaining higher powers when they are in the third form, because they really don't know if there won't be a fourth...

 

[Stoutstien]

Single targets are always hard to pull off in 5e without it just breaking down one way or the other. Saying that you can have something that feels more challenging than it really is. Glabrezu have at will dispel magic which can catch parties off guard if they utilize lots of spells, Storm giants/empyrean have a extremely long ranged attacks and good ways of getting the drop on parties, and dragon turtles are fun if you switch swim speed for burrowing.

 

[Lyxen]

Single targets are always hard to pull off in 5e without it just breaking down one way or the other.

Yes, this is why I pointed towards Angry DM's solution, but there are others, in particular the official mythic monster that I've used a number of times to great effect (the advantage being that it's supported by DDB), or others from Matt Colville, Giffyglyph, etc.

 

[Quickleaf]

A marut could be fun. You could even splice it with the eidolon's Sacred Animation ability to make sure it lasts long enough for a thrilling fight.

Or an elder elemental like a leviathan or elder tempest, with some environmental hazards could fit your ask.

 

[Paul Farquhar]

Leviathan wouldn't fit through the door!

For this particular encounter I've decided to go with a slightly tweaked version of Polukranus, the legendary hydra from Theros, genericed to "Ancient Hydra".

My players are a pain "we want to play all the way to level 20!" grumble grumble

 

[Quartz]

An idea for you: when they cut one of the heads off it becomes an independent floating hydra head. Which needs killing.