Proper retinue for a dragon - mathematically and ny RAW

[Pinjata]

So I'd like to give out some info but not all of it and off that I'd like to ask for help for calculation of encounter.

Encounter consists of an adult dragon(CR 13). Party that will face it is of proper level. How many creatures of what CR could accompany this dragon per CR/Encounter difficulty?

Only adittional guidance I can give is that encounter may be so hard it will put two characters into negatives.(well, old edition term, but yeah).

Got anything for me, math-wizs?

thanks :)

[Lolzyking]

you need to number of players, their levels, (classes helps too) to make a encounter, just the dragons CR doesn't help.

You can make a very deadly encounter for players with a dragon involved in multiple ways.

1) give the dragon lair actions.

2) give the dragon a large contingent of kobold, despite their low CR pack tactics and action economy will allow them to shred a party and muck up the combat area stopping the parties melee from getting in range to fight the dragon without provoking Opportunity attacks

3)a few Elite guards that might be able to lockup the party mage in a counterspell duel or lockdown a paladin from tanking for the squishier allies.

[JackPhoenix]

Here (http://kobold.club/fight/#/encounter-builder) you go. Set the level and number of the characters in party, choose the adult dragon from the list, and then add kobolds or other combatants to taste until intended fight difficulty is reached.