Checking some CR assumptions

[AvatarVecna]

Alright, so I'm considering running a kinda odd game here ITP, and I decided I'm actually gonna plan ahead on some things for once. I have a couple weird thoughts on CR, and I wanted to run them by the Playground think tank, see if I'm on the right track or completely off base.

1) Legendary Actions, Lair Actions, and Regional Effects are taken into account when determining the CR of a monster. That is to say, an Aboleth (CR 10, Legendary Actions, Lair Actions, Regional Effects) is considered just as challenging a fight as a Deva Angel (CR 10, no Legendary/Lair Actions, no Regional Effects).

2) NPCs built as a PC of lvl X with all the class features and ribbons constitute a threat of CR X as well; this makes X DMPCs a quadruple-deadly challenge for X PCs of the same level.

This second one is particularly troubling, since mixing CR and class levels is something that I intend to happen quite a bit in this game on both sides of the screen, and I want to have some idea of whether it's balanced or not to tradeoff class levels and CR.

[Ninja_Prawn]

1. Should be a safe assumption, but possibly dicey at high CRs. When I calculate CRs for homebrew monsters, I include Legendary Actions... I've never made a monster with a Lair Action, and I don't know whether the MM factors them in.

2. Not a safe assumption at all. Class levels do not translate directly to CR; usually the CR of a PC is smaller than their ECL. PCs are generally more glass-cannony than monsters, too, which makes them harder to balance, plus they get lots of abilities that don't work well on monsters. I don't know the specifics of your game, but using PCs as monsters is not usually something I'd recommend.

[Laserlight]

2) NPCs built as a PC of lvl X with all the class features and ribbons constitute a threat of CR X as well.

I wouldn't think so, since for 4PCs of L6 (my party for tonight), two Gladiators (CR5) makes a Hard, almost Deadly encounter. A Gladiator has 112hp, a bit more than twice what the average L6 PC would have; he gets 3 attacks at +7 for 2d6+4 (average 33/turn), which is again about 1.5 to 2 times what the party members do (mostly 2 attacks for 1d8+4 for average 17, although my rogue averages 24 including SA dice).

PCs probably have a bit better defenses, but the main thing is that they're more flexible (my rogue wouldn't go one-on-one with a Gladiator, he'd use his +11 Stealth or +10 Persuasion to get past him) and the person playing a PC can devote his all his attention to that PC's sneaky tricks instead of splitting his attention among all the monsters plus the environment.