5e Help with CR please

[stoneaged]

I know it might seem strange stat line but was designed for something specific. When I try to calculate the CR does not come out to what my gut says. Was hoping for opinions on the best CR for it.


AC 18
HP 128 21d8 +21

str6 dex18 con13 int17 wis16 cha18

saves dex+9 int+8

stealth+9 (+12 in dim light or darkness)

dmg vulnerability radiant

dmg resistance acid, cold, fire, lightning, thunder,
bludg, piercing, and slashing from nonmagical attacks

dmg immunity necrotic, poison

condition immunity charmed, exhaustion, frightened, grappled, paralyzed,
petrified, poisoned, prone, restrained, spell magic jar

darkvision 60ft

when in dim light or darkness can take hide action as a bonus action

sunlight weakness

regeneration

attk action
+12 to hit dam 1d4+7 sneak attack of 3d6 (+3 dagger of wounding)
or
cause a dc18 sv vs int or become stunned until makes an int save

8th level caster (wizard)

[PhoenixPhyre]

First thing I notice is that it has crap for damage for the HP. 20 DPR is offensive CR 2. But then it has a save DC of 18 and attack mod of +12? That bumps the adjusted offensive rating up by 4, to oCR 6. See note 2

Defensively, 128 HP is dCR 4. AC 18 bumps that up by 2, to dCR 6. All the resistances and (especially) immunities bumps it up by 1, maybe. Call it dCR 7.

Final CR is either 6 or 6.5, so round down to 6.

Overall thoughts: This will not be a fun fight for anyone, as written, at least IMO. Low offensive output means it's not a threat...except that stun with a crazy-high DC on a weak save. That just feels cheap. Generally, hard CC requires either a WIS or CON save.

NOTE 1: The spellcasting is impossible to weigh because you haven't picked spells. That may completely obviate the low damage output, or may be irrelevant.

NOTE 2: Generally, having large adjustments, especially upward due to AC or attack bonus is a sign that the monster isn't going to work well. It's a design smell. If you want this to be offensively CR 6-ish, give it multiattack and drop the attack bonus. If you want it to be CR 8-ish, give it at least 3x the damage output (ie multiattack with 3 attacks, each proccing sneak attack). As a note, a +12 attack bonus is suitable for CR 25 monsters!!!

NOTE 3: Generally, for very special-purpose monsters, CR loses most of its meaning. In fact, I'd recommend that if you're experienced enough to feel comfortable running a very weirdly-designed (relative to the norm) monster like this, you're probably experienced enough to just eyeball difficulty and ignore CR entirely. To be honest, it's what I do. I rarely calculate CR these days, backfilling it so that the calculated numbers come out (basically picking the CR that gives the right proficiency bonus).

[stoneaged]

First thing I notice is that it has crap for damage for the HP. 20 DPR is offensive CR 2. But then it has a save DC of 18 and attack mod of +12? That bumps the adjusted offensive rating up by 4, to oCR 6. See note 2

Defensively, 128 HP is dCR 4. AC 18 bumps that up by 2, to dCR 6. All the resistances and (especially) immunities bumps it up by 1, maybe. Call it dCR 7.

Final CR is either 6 or 6.5, so round down to 6.

Overall thoughts: This will not be a fun fight for anyone, as written, at least IMO. Low offensive output means it's not a threat...except that stun with a crazy-high DC on a weak save. That just feels cheap. Generally, hard CC requires either a WIS or CON save.

NOTE 1: The spellcasting is impossible to weigh because you haven't picked spells. That may completely obviate the low damage output, or may be irrelevant.

NOTE 2: Generally, having large adjustments, especially upward due to AC or attack bonus is a sign that the monster isn't going to work well. It's a design smell. If you want this to be offensively CR 6-ish, give it multiattack and drop the attack bonus. If you want it to be CR 8-ish, give it at least 3x the damage output (ie multiattack with 3 attacks, each proccing sneak attack). As a note, a +12 attack bonus is suitable for CR 25 monsters!!!

NOTE 3: Generally, for very special-purpose monsters, CR loses most of its meaning. In fact, I'd recommend that if you're experienced enough to feel comfortable running a very weirdly-designed (relative to the norm) monster like this, you're probably experienced enough to just eyeball difficulty and ignore CR entirely. To be honest, it's what I do. I rarely calculate CR these days, backfilling it so that the calculated numbers come out (basically picking the CR that gives the right proficiency bonus).

I appreciate your feedback. I knew it was a mess. I was having a problem with trying to calculate things based on an unoptimized multiclass (the boss is a former player's character that was absorbed into a creature.) The save DC was a pure typo but it would of probably still been too high from what you said. The attack bonus was based on proficiency bonus + ability mod + weapons magical modifier. Same thing with the AC. It was based on magical armor + dex. I only had one attack as that's what the character originally had. The spell list would of been mostly based around a couple of summon spells.

I guess I will have to go back to the drawing board and probably go with the suggestion a friend gave when asked his opinion on the CR. Just go based on a creature out of the MM and beef it up a tiny bit.

[PhoenixPhyre]

I appreciate your feedback. I knew it was a mess. I was having a problem with trying to calculate things based on an unoptimized multiclass (the boss is a former player's character that was absorbed into a creature.) The save DC was a pure typo but it would of probably still been too high from what you said. The attack bonus was based on proficiency bonus + ability mod + weapons magical modifier. Same thing with the AC. It was based on magical armor + dex. I only had one attack as that's what the character originally had. The spell list would of been mostly based around a couple of summon spells.

I guess I will have to go back to the drawing board and probably go with the suggestion a friend gave when asked his opinion on the CR. Just go based on a creature out of the MM and beef it up a tiny bit.

That last sentence is probably the best way of doing things. Trying to make monsters using PC builds is...fraught with peril. Doable, but you have to know all the pieces.

One other question--is this intended for a solo fight? If so...rethink that. Solo fights require very very special design to not be frustrating messes.

[Yakk]

If this is an absorbed copy of a former PC, I wouldn't use PC rules for it. I'd be inspired by PC rules.

The former PC was an 8th level wizard. So, what spells did that wizard tend to use? Make abilities like those spells.

Simple method 1:

Defensive CR: (HP/17, min 4) + (AC/2) - 11, min 0
Offensive CR: (DPR/6.5, min 1) + (ATK Stat bonus)/2 - 1.5, min 0

CR = average of Offensive and Defensive.

Actual attack bonus = proficiency + ATK Stat bonus.
Actual save DC = 8+proficiency + ATK Stat bonus.

This won't be accurate for creatures at or under CR 1 or at or over CR 20.

Suppose we want a CR 10 foe, balanced offensive and defensive.

Give it 15 AC, but it has shield for +5 on a reaction.

It has a displacement effect, worth +3 AC (disadvantage on attacks until it is hurt).

It has magic resistance "worth" +2 AC, and proficiency in Int and Wis saves.

Total effective AC is 25.

We want a defensive CR of 10, so 10 = -11 + (HP/17) + (25/2), or 8.5 = HP/17, or HP=145.

Next, offensive. We'll give it 3 legendary actions and split its damage budget into (2 on turn) and (1 per legendary action) - so 5 parts.

It is a wizard, so we'll add in a recharge 6 big blast that does 5x units of damage that replaces its standard action. This is +3 parts, which we divide by 3 (3 round DPR) so 6 parts of damage.

It has 20 intelligence (+5 ATK stat bonus) - so DPR can be calculated:

(DPR/6.5) + (5)/2 - 1.5 = 10
DPR = 9*6.5 = 58.5.

We divide by 6 for about 10 per share.

At will: 20
Legendary: 10
Big Burst (recharge 6): 50

Legendary Actions:
Thunderstep (3d10 aoe, con save, teleport 90 feet) 2 legendary actions
Shocking Grasp (2d8 vs AC, blocks reactions) 1 legendary action
Fire Bolt (2d10 vs AC, ranged) 1 legendary action
Magic Missile x2 (1d4+1 x2, auto-hit, strength save or be pushed 10') 1 legendary action
Ray of Enfeeblement (Ranged attack, target deals 1/2 damage with str-based attacks, con save to end) 1 legendary action

Bonus Action: Magic Missile x2 (1d4+1 x2, auto-hit, strength save or be pushed 10')

At-Will spells (or nearly at-will).
Scorching Ray (2x 2d6 damage ranged attacks)
Acid Arrow (4d4 acid damage on it, 2d4 next round; if miss, 2d4 acid damage)
Call Lightning (3d10 lighting damage 5' radius)

Big Boom: (recharge 6)
Double Fireball (6d6 damage, save for half) followed by a second Fireball (6d6) as a bonus action

Spell save DC is 17, spell attack roll is +9.

...

Now in your case, you want a mixed wizard and sneak.

So I'd shave down the magic a tad and up the sneak. I might make actions mostly be sneak-type actions, and legendary be spells.