D&D 5E Legendary monsters are not solo monsters

[Tormyr]

So I finally finished my Monster CR calculation spreadsheet and plugged the Spirit Naga in. A few interesting things came out of it. The only way I was able to get to CR 8 was to:
*Use lightning bolt for 3 rounds (1 at 5th level, 2 at 4th level) and average hitting two targets each round
*Use the immunity to poison to double the effective hit points even though there is only 1 immunity (poison) instead of several.

Using lightning bolt at the maximum levels possible was not what I first looked at to figure out the most effective DPR, but it turned out to be the right answer in the end. I would not have expected to need to use the damage immunity to double the effective hp since the guidelines say to only use the effective hp multipliers if there are several immunities or resistances. However, it was the only way I could get to the Spirit Naga's CR of 8.

So, setting the spreadsheet up with the Spirit Naga's stats so that I came up with a CR of 8, I adjusted the actual HP up by 150. If the doubling of effective hp had not been there, it would have only resulted in a modest CR bump of a few levels. I was looking for a CR of 17. However, because of the doubling of effective hp, the Spirit Naga's effective HP was 450. When everything averaged out, the CR was 16. So this was interesting. Just bumping HP by how many CR levels you want to change may work, but it would require more checks of creatures to see if it worked regularly or if this was dumb luck.

 

[pemerton]

While the quick increase in CR using hp was not perfect, It got the job done. The CR of the creature increased to allow it to survive multiple rounds against 7 PCs. By using hp instead of AC, DPR, or AB, The CR and staying power of the creature increased without increasing the risk of a 1 shot kill from the creature. While it would have been more accurate to calculate out the change in effective hp, and average the new defensive CR versus the existing offensive CR, this did a good enough job on the fly.

Perhaps I've misunderstood you, but what you are describing is one part of the 4e approach to solos: more hit points than is typical for a monster of their level/CR.

The other thing 4e does is add in bonus actions, recoveries etc (generally a more clunky version of legendary resistance and legendary actions). Did you do anything like this for your naga?

 

[Tormyr]

Perhaps I've misunderstood you, but what you are describing is one part of the 4e approach to solos: more hit points than is typical for a monster of their level/CR.

The other thing 4e does is add in bonus actions, recoveries etc (generally a more clunky version of legendary resistance and legendary actions). Did you do anything like this for your naga?

No, in this case, all I did was increase the hp. The fast and loose method of scanning the CR table on page 274 of the DMG and adding the difference in HP between the CR of the creature and the CR I wanted it to be. However, using that method can add only half the CR change you want or double it depending on any effective hp adjustments it has.

I could have given a legendary action and resistance, but that gets harder to adjust on the fly. Effective hp goes up by 30 for each legendary resistance and DPR can increase with legendary actions. This would be easy on a spreadsheet, but difficult on the fly.

In the long run, it is difficult to adjust CR on the fly. It takes me about 5 minutes with my spreadsheet. The longest part of the time is figuring out what is the most effective attack strategy and calculating the average damage for 3 rounds. This is not too bad for prep, but people are going to get bored waiting for that calculation.

 

[pemerton]

No, in this case, all I did was increase the hp.

Did you find your naga had problems with action economy, or did its hit points give it enough longevity to get some actions achieved?

 

[DaveDash]

Increasing hitpoints is generally way more effective than legendary actions/resistances, because those things don't help you when you're dead in the first round.

Anything in my games now that is meant to be solo gets max hit points. I also don't increase the CR either (XP awarded) because being solo and lack of action economy is a huge disadvantage in this edition, but I do calculate its 'effective' CR when trying to determine encounter difficulty.

 

[Tormyr]

Did you find your naga had problems with action economy, or did its hit points give it enough longevity to get some actions achieved?

It did fine with action economy, partially because it didn't fight head on. I could have given it legendary actions so that it did more, but then I would have had to drop the hp.

The way things unfolded:

Setup:
The adventure says that the naga is the inhabitant of a cave complex inhabited by the actual bad guy. The naga is annoyed at being intruded upon and demands an apology and a gift of 1000gp. Well this party doesn't part with their money willingly and tends to shoot first. The halfling rogue /monk stealthed up while the rest of the party was further back and saw the naga. As she was getting ready to head back and report, the high elf eldritch knight stumbled forward and was noticed by the naga. As the fighter turned to get away, the naga used hold person and talked with the fighter. The human war cleric came up behind the fighter and tried to defend her, but the naga was having none of it and told the cleric to bring money. The tiefling wizard and cleric don't part with their money, and organized an ambush.

Ambush:
The wizard was behind some of the others and said, "Here's your money!" and shot Melf's acid arrow. The cleric was also ready for the ambush, so they got to act in the surprised round. The wizard got to go again at the top of the initiative order. Then the naga went and used dimension door to teleport far behind the party. The party thought it was gone and started exploring further forward in the caverns. They stumbled into a group of drow with a priestess of Lolth. The cleric cast daylight to impose disadvantage on their attacks.

Revenge (or not):
While the group started attacking the drow, the naga snuck up behind them and let loose a lightning bolt that hit 5 of the 7 party members. 1 problem. In the center of the group was the half-gnoll oath of the ancients paladin. At 8th level he confers a 10' aura that adds 1 to saving throws and confers resistance against magic. Almost everyone made their saving throws each time and had resistance, so damage was typically ~7 per PC (and the rogue had 0 damage from evasion). Frustrated, the naga turned around and dealt with the human monk that was behind him, dealing a bit more damage with blight. In the end, he promised that he could not be dealt with permanently and would be back as the monk finished him off.

All of this took about 7 to 9 rounds. If the party had focused on the naga, I think it would have taken about 3-4 rounds of actual combat which seems to be the magic number when dealing with a single enemy. With 7 attacking it, it would have fallen in the first round if it only had the normal 75 hp. The 225 hp allowed it to last long enough to get several attacks out. It would have been pretty devastating without the Paladin protecting everyone.

All in all, I was happy with how the adjustment turned out. The frustrating thing was the darn paladin (and this from someone whose favorite class is the paladin).

 

[Quickleaf]

[MENTION=6776887]Tormyr[/MENTION] Nice play report

With your Oath of Ancients Paladin, sounds like some anti-clustering measures might help increase the challenge of your future encounters (when you're feeling so inclined). Spells and effects that push PCs away from each other (e.g. thunderwave). Spells and effects which turn one PC against the others or make one PC "toxic" (e.g. the walking bomb from Dragon Age comes to mind...not sure if 5e has an equivalent). Spell and effects which are optimized against clustered parties (e.g. chain lightning & cloudkill). Spells and effects that target the terrain not the PCs (e.g. earth to mud). Volley or Explosive/Area ranged weapon fire (e.g. Ranger NPCs or siege weapons). Multiple goals in different areas of the encounter zone that must be engaged simultaneously (e.g. fighting on two fronts with a timed puzzle in the middle). Temptations designed to lure one or two PCs from the clustered party (e.g. an honor duel for the paladin). And so on.

 

[Tormyr]

[MENTION=6776887]Tormyr[/MENTION] Nice play report

With your Oath of Ancients Paladin, sounds like some anti-clustering measures might help increase the challenge of your future encounters (when you're feeling so inclined). Spells and effects that push PCs away from each other (e.g. thunderwave). Spells and effects which turn one PC against the others or make one PC "toxic" (e.g. the walking bomb from Dragon Age comes to mind...not sure if 5e has an equivalent). Spell and effects which are optimized against clustered parties (e.g. chain lightning & cloudkill). Spells and effects that target the terrain not the PCs (e.g. earth to mud). Volley or Explosive/Area ranged weapon fire (e.g. Ranger NPCs or siege weapons). Multiple goals in different areas of the encounter zone that must be engaged simultaneously (e.g. fighting on two fronts with a timed puzzle in the middle). Temptations designed to lure one or two PCs from the clustered party (e.g. an honor duel for the paladin). And so on.

Thanks for the ideas. One of the things I thought about doing, but ultimately decided not to do, was to have it use dominate person against 1 of them in the middle.