Calculating Encounters with Allied Monsters

[ZenBear]

I typically use this encounter calculator (http://dhmstark.co.uk/rpgs/encounter-calculator-5th/) to build my encounters, but it lacks an option to measure when the party has monsters fighting on their side. Does anyone know of a similar website or just have their own formulas for determining the CR of an encounter with this in mind?

[BloodSnake'sCha]

I typically use this encounter calculator (http://dhmstark.co.uk/rpgs/encounter-calculator-5th/) to build my encounters, but it lacks an option to measure when the party has monsters fighting on their side. Does anyone know of a similar website or just have their own formulas for determining the CR of an encounter with this in mind?

Use recalculate the encounters with the allies as additional party members. I think you should use the CR as the monsters level for the calculation.

For example:
3 lv3 PCs and 2 allies CR3 monsters will be like 5 lv3 PCs.

My advice is based on the wording on the Polymorph spell on turning someone to a beast.

[JNAProductions]

Level 3 PC=/=CR 3 Monster

Multiply CR by 1.5 for a VERY ROUGH ESTIMATE of their effective level. Very. Rough.

[Man_Over_Game]

Added monsters don't act like players, so I'm not sure if they should be calculated like ones.

Rather, I think a better way of doing it is subtracting value from the enemy team equal to the value of the NPC allies.

Or, in other words, calculate the NPC allies as a total. Now deduct that total from the enemy team, and scale the enemy team back up.

So if the allied team has two CR 1 guards, you add that much value to the enemy team. The easiest way of doing it would be to add enemies of equal CR, so that neither side has any kind of numbers advantage.

[Rukelnikov]

This is a system that @MaxWilson posted today in the artificers thread, sounds like you may be interested in it.

"I should mention that I've started giving summons and hirelings a share of the combat XP, which IMO is the only way to make summoning spells and Animate Dead a situational tactic instead of an obvious go-to tactic. (Your share of the total XP is your CR or level, rounded up, divided by total CRs or levels also rounded up. Four level 8 PCs and eight CR 1/4 conjured wolves will result in PCs losing out on 20% of total XP, but four level 8 PCs and one conjured CR 2 Giant Constrictor Snake will only cost them about 6% of their XP, making the higher-CR Conjure Animal options more relatively attractive for tough-but-not-deadly fights.)

Without this XP tweak, purchased mastiffs would be overpowered, and Beastmasters-with-a-bonus-action-command would be somewhat overpowered."

[brainface]

fwiw, i do the super super lazy "and then an ally and a monster start shadowboxing and i pretend to roll dice"

[Bjarkmundur]

I have done no research one the subject whatsoever, but a quick comparison of a level 3 EK and this (http://blogofholding.com/?p=7338/) study on monsters from the monster manual, leads be to believe that a level 3 PC is more akin to a CR1/2 to CR1 monster.
Maybe this is a different discussion.

[Bjarkmundur]

So if the allied team has two CR 1 guards, you add that much value to the enemy team. The easiest way of doing it would be to add enemies of equal CR, so that neither side has any kind of numbers advantage.

This seems like a reasonable solution.

[DrKerosene]

I prefer to have NPCs face off against enemies that aren’t really there, if possible. Just having the allied NPCs and “extra enemies” basically step outside of the main action, unless I need an excuse to interfere with the current direction of things. Like a timely Healing Word.

[Man_Over_Game]

This seems like a reasonable solution.

Just basic algebra.

If a CR calculator is trying to solve

X = Y

And

Z = X + 1

How do you solve

Z = Y + ?