CR Calc: When to Apply DR Multiplier vs other EHP Increases?

[Wryte]

I'm trying to calculate the CR of a creature I'm designing, and running into a snag. The creature in question has both Resistance to nonmagical weapon damage, and Regeneration.

According to the CR guidelines in the DMG, this damage resistance is worth a 1.5x modifier to its effective hit points (for a tier 2 CR), while the regeneration is worth a simple +(3x regen/turn).

So, in calculating the creature's total effective hit points, do I apply the Resistance multiplier first and then the Regeneration additive, or the other way around?

In other words, does the calculation become

(HP + Regeneration) x Resistance

or

(HP x Resistance) + Regeneration

?

To put some simple numbers to it, let's say the creature has 100 actual HP, regenerates 10 HP/turn for +30 effective HP, and has a 1.5x resistance multiplier for a CR 5-10 creature.

Does this become (100 + 30) x 1.5 = 195 EHP = CR 9, or is it (100 x 1.5) + 30 = 180 EHP = CR 8?

[PhoenixPhyre]

I'm trying to calculate the CR of a creature I'm designing, and running into a snag. The creature in question has both Resistance to nonmagical weapon damage, and Regeneration.

According to the CR guidelines in the DMG, this damage resistance is worth a 1.5x modifier to its effective hit points (for a tier 2 CR), while the regeneration is worth a simple +(3x regen/turn).

So, in calculating the creature's total effective hit points, do I apply the Resistance multiplier first and then the Regeneration additive, or the other way around?

In other words, does the calculation become

(HP + Regeneration) x Resistance

or

(HP x Resistance) + Regeneration

?

To put some simple numbers to it, let's say the creature has 100 actual HP, regenerates 10 HP/turn for +30 effective HP, and has a 1.5x resistance multiplier for a CR 5-10 creature.

Does this become (100 + 30) x 1.5 = 195 EHP = CR 9, or is it (100 x 1.5) + 30 = 180 EHP = CR 8?

I'm pretty sure it's supposed to be multiplied at the end--regeneration on a resistant chassis is worth more effective HP (because to chew through +X HP/turn you have to do more than X damage/turn by the multiplier).

So in this case I'd say 180 EHP. CR's an art rather than a science--as you can see in the spreadsheet at my signature, there are lots that deviate strongly from the "book calculated" values, mainly because of play-testing.