Level Up (A5E) Monster Creation: CR vs Resistances, Immunities, and Legendary Resistances

[TheDungeonMathster]

The designing monsters section of the Monstrous Menagerie seems to account for offensive abilities, but how does it account for resistances, immunities, and legendary resistances?

For example, the following creature seems as though the defensive traits (resistances, immunities, and legendary resistance) should adjust CR or HP.

 

[TheDungeonMathster]

I should also include traits like Magic Resistance.

 

[W'rkncacnter]

iirc they didn't bother giving advice on resistances/immunities since you needed to get to like 11 before they'd even bump CR by 1, and legendary resistances are counted for when you consider a creature legendary.

now, my question is how in the WORLD does a BEHOLDER wear BRACERS?

 

[TheDungeonMathster]

iirc they didn't bother giving advice on resistances/immunities since you needed to get to like 11 before they'd even bump CR by 1, and legendary resistances are counted for when you consider a creature legendary.

now, my question is how in the WORLD does a BEHOLDER wear BRACERS?

 

[W'rkncacnter]

View attachment 376765

...that sounds...uncomfortable...

 

[Steampunkette]

The general rule of thumb, I think, is to reduce HP based on Resistance and Immunity. If they take half damage from -everything- then cut their HP in half, for example, since it's the same as having double the HP outside of one or two edge cases cough cough Power Word Kill cough

And reduce HP proportionally based on resistance to various damage types. BSP are the most common and so count for the biggest bump in HP. Then comes Fire, Lightning, Cold... you get the idea.

 

[TheDungeonMathster]

Yeah, I thought so as well; however, nowhere in the creature design part of the Monstrous Menagerie do they mention such modifications. Moreover, going through their stat blocks, I don't see such accommodations being given to monsters with considerable amounts of resistances. It's strange.

 

[TheDungeonMathster]

I am considering a hybrid integration with the original 5E monster creation rules. Nothing too fancy, but something with a bit more... guidance in these situations (the campaign I am converting goes to 20th level and there are a LOT of resistances, immunities, and legendary resistances as the PCs progress).

Here is what I have scavenged from the OG rules:

• Reduce HP target by n for every use of legendary resistance, where
  • n = 10 for CR <= 4
  • n = 20 for CR 5 - 10
  • n = 30 for CR >= 11
• Abilities that grant no damage on successful saves and 1/2 damage on failed
  • Decrease AC target by 1
• Magic Resistance
  • Decrease AC target by 2
• Hide as Bonus Action
  • Decrease AC target by 2
• Any ability that allows 0 HP to become 1 HP, decrease HP by n, where
  • n = 7 for CR <= 4
  • n = 14 for 5 <= CR <= 10
  • n = 21 for 11<= CR <= 16
  • n = 28 for CR >= 17
• Take the greater of the following two deductions:
  • Resistance to 3 or more damage types (BPS count as 3), reduce target HP to
    • 1/2 of target HP in text for CR <= 4
    • 2/3 of target HP in text for 5 <= CR <= 10
    • 4/5 of target HP in text for 11 <= CR <= 17
  • Immune to 3 or more damage types, reduce target HP to
    • 1/2 of target HP in text for CR <= 10
    • 2/3 of target HP in text for 11 <= CR <= 16
    • 4/5 of target HP in text for CR >= 17

I know it seems a bit more complex, but it is automated on my end.

 

[TheDungeonMathster]

Well, I ran a session with my modifications (lowering HP based on defensive abilities). Let me say that it was a bit too easy. I will likely go back to the standard method presented in MM from this point forward.