D&D 5E Insight into value of petrification and paralyzation in terms of xp value when building monsters?

Anyone got any insight into how to handle paralyzation, petrification and other 'game-ending' abilities for monsters when figuring out their xp value? The examples in the MM don't shed a ton of light. Anyone subjected these abilities to sufficient analysis to be able to say with confidence how to 'cost' them?

I think the best way to handle paralysis influence to CR is to check if the average damage of 3 rounds assuming the target gets paralyzed in the first, and saves on their first save following if they can end the paralysis early by saving at the end of a turn, is higher than 3 rounds average of the monster's attacks without the creature being paralyzed. If it is, use it as the average damage figure for determining CR and use the save DC as the calculating factor of offensive CR rather than the attack bonus.

As for petrification... I don't really think that an adjustment to CR is needed. I mean, a cockatrice has petrification and is CR 1/2, so the power to petrify obviously isn't treated as inherently dangerous by the design of the game.

AaronOfBarbaria said:

As for petrification... I don't really think that an adjustment to CR is needed. I mean, a cockatrice has petrification and is CR 1/2, so the power to petrify obviously isn't treated as inherently dangerous by the design of the game.

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Alternatively--and, IMO, much more likely--the designers are of the opinion that such abilities are not within the purview of CR, despite their significant impact on encounter difficulty. Low-CR creatures with dangerous, even lethal save-based attacks are a Thing in 5e, as I had understood it.

EzekielRaiden said:

Alternatively--and, IMO, much more likely--the designers are of the opinion that such abilities are not within the purview of CR, despite their significant impact on encounter difficulty. Low-CR creatures with dangerous, even lethal save-based attacks are a Thing in 5e, as I had understood it.

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That's basically what I was getting at - there is no exact measurement of how petrification affects the targeted character, so if there are good chances to avoid it there is no measurable effect upon CR.

AaronOfBarbaria said:

That's basically what I was getting at - there is no exact measurement of how petrification affects the targeted character, so if there are good chances to avoid it there is no measurable effect upon CR.

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Er...no, that's not what I was saying.

I was saying that there can be measurement of it, the designers just decided that CR wouldn't measure it. Effects like this have measurable impact in other games (if sometimes only loosely, e.g. 13th Age).

I also have some pretty big questions about what "good chances to avoid it" means. Excluding your two good (Proficient) saves, any 5e character gets worse at saving against most monster effects as level goes up--possibly getting down to failing 80% of the time. This may be less meaningful for low-level monsters, but a truly "bad" save (no Prof, low/dump stat) may be a straight D20 check versus a DC of 12-14. So...what constitutes "good chances to avoid it"?

EzekielRaiden said:

I also have some pretty big questions about what "good chances to avoid it" means.

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Depends on the particular source of petrification. Cockatrice, for example, has to hit you with an attack and then you have to fail two saves before you are actually petrified (at a low save DC), and even at that point we are talking about 24 hour petrification rather than entirely permanent.

Other sources of petrification tend to keep at least to the 2 failed saves to truly take effect, and some include further means of avoiding them like averting your eyes from a medusa's gaze.

EzekielRaiden said:

Excluding your two good (Proficient) saves, any 5e character gets worse at saving against most monster effects as level goes up

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I think that is a mismatching of player expectation and system expectation, since the system gives plenty of opportunity to shore up your weaker saves and makes it so that being proficient in your stronger saves is all it takes to make you "good enough" at them, and higher level parties are given plenty of opportunities to further cover the weakness that low saves might otherwise be (that paladin aura for example). Plus, 5th edition is much less expectant of parties to be facing "same level" opponents exclusively or even a majority of the time.

I don't think "completely disregard it" is the way it's valued in the creatures in the MM, though. By the numbers, a ghoul would come out at CR 1/2, not CR 1; a grell at CR 1/2 or 1, not CR 3; a cockatrice at between CR 0 and 1/8, not CR 1/2; a medusa at CR 4, not CR 5; and a basilisk between CR 1 and 2, not CR 3.

On the other hand, a gorgon comes out at its listed CR- CR 5- leading me to believe that petrification or paralyzation is valued more at lower levels. Or maybe it's because it's limited use. I don't really know; I haven't been able to suss it out exactly.

Like I said, I would especially love to hear from anyone who has analyzed the numbers- maybe [MENTION=84774]surfarcher[/MENTION]?

When I am beefing up a monster, and I get into this type of situation that is not listed on that chart in the DMG, I simply round up. In other words, if the defensive CR rating is 2 and the offensive CR rating is 3, the average is 2.5; I then round up to 3.

Not a very statistical analyses, but it has worked for me so far (Party is level 12)...

I'm in agreement that in general they're not worth much as far as boosting CR if it is damage OR using the ability. Something like an Ultroloth does pitiful damage but has a stun that is in addition to their attacks and I think that is factored into its CR a bit.

I disagree with the way WotC calculates CR of encounters a bit because it ignores the force multiplication possibility of these abilities. If you're throwing 4 things at the party that all do the same damage then critter wise the party could by fighting over 3 rounds:
4,4,4=12 critters worth of damage

If one of them can burn their action to AoE paralyze and we assume paralysis is worth roughly double damage (double dice + advantage) and a single PC fails 2 saves then over 3 rounds you'd see:
6,8,4=18 critters worth of damage

if no PC fails a save then you'd see:
3,4,4=11 critters worth of damage

As an encounter, it may be 50% harder offensively from the NPC's perspective (and possibly defensively too with 1 PC out of the fight for 1+ round) if the paralysis works but not much different if it fails (around 10% easier). As a solo creature though it would probably perform about the same as a creature without the ability. This is assuming fairly easy to hit AC on part of the PCs, if the monsters are missing a bunch then burning a turn of attacks that would probably miss for a chance to gain advantage for all of your allies is going to be a game changer.

I personally ignore the "multiply the encounter xp" thing for multiple creatures of a similar CR, unless one or more of them has a big status effect in which case I will follow those rules.-

Well, for the record, I just tweeted Chris Perkins about it. We'll see if he replies.