Help me evaluate my party's ability to take the BBEG

[Borria]

Ilox/Carmina/Sherlocke turn back now!

Hi all, I have a party of 3 9th level characters that have quite a few upgrades as they are in a high magic world. Their final boss in an upcoming session will be a green dragon, but I'm trying to pick out the appropriate challenge level for them for this encounter. I want it to be difficult, I am comfortable with them not winning. However, my encounter design this far has not been all that threatening, save one PC death that did require the party to go ask for some favors to bring them back. According to the MM a young green dragon is CR 8 which might be about right for a party of 3 rather than 4 or 5, but with their various buffs I want to find the right difficulty level for the final fight. Things of note about the party:

- They consist of a moon druid, an armorer artificer, and a shadow sorcerer.
- Each party member has a +1 focus for their spellcasting
- The sorcerer is wearing armor despite normally lacking proficiency (they can still cast and everything), so their ac is 18ish
- The sorcerer and the artificer have cha and int 22 respectively due to reading the stat-boosting books
- None of the players here are powergamers by any means. The sorcerer has only ever used their metamagic for spell slots or empowered spell and likes to lightning bolt things. The moon druid doesn't tend to wildshape.

Some things I'm thinking to modify the difficulty are to give this dragon extra spellcasting (which would fit their role in the world), give it some mooks (I know it's easier on the party but if possible I'd like to keep this a 1v3), or just buff up it's hp or defensive prowess in some way.

What thoughts do you all have for me? How can I make this encounter managable, challenging, and epic? This has been my first campaign so I would love an epic battle to end things off. Thanks in advance!

[Angelalex242]

Heh.

If I were you, I'd do my best to make the fight highly difficult to win if the Druid doesn't wild shape and the sorcerer doesn't metamagic. Make them use the tools on their sheet they don't typically use.

[Galithar]

Okay, so with the buffs roughly calculated as an extra level for your PCs you should be looking at a CR 13 creature to hit a deadly encounter for your PCs.

If they are fresh and full spells etc. this should give a chance at a PC dying. You say they are powergamers or even fight very optimally so I think this should do a good job of putting fear into them while still being winnable.

A Young Green Dragon is CR 8. They WILL stomp this into the ground with no effort.

An Adult Green Dragon is CR 15. A little higher than we want. Optimized players could probably handle it.


So before I spend too much time trying to make a middle power dragon (possibly just the stats of another color and swap breath weapons) do you expect your players to be close to full resources walking in? What are the approximate Con saves of the group? How likely are they to bunch up and let the breath weapon tear them apart?

[Borria]

Okay, so with the buffs roughly calculated as an extra level for your PCs you should be looking at a CR 13 creature to hit a deadly encounter for your PCs.

So before I spend too much time trying to make a middle power dragon (possibly just the stats of another color and swap breath weapons) do you expect your players to be close to full resources walking in? What are the approximate Con saves of the group? How likely are they to bunch up and let the breath weapon tear them apart?

Thanks for the reply! I believe the sorcerer is at con 14 and the artificer and druid are around con 16 and none of them have taken resilient or warcaster iirc. They may well have ran into another pre-final boss (some appropriately cr'd demon), but it wouldn't be that strange for them to get a full rest in between fights, or for me to give them a "cutscene" in between fights where the dragon knocks them out and they awake in his lair later for the fight (this would not be OOC for the dragon to do). Let's say for the sake of argument they have everything available to them.

Also, just to make sure we are on the same page they are NOT powergamers, and frankly don't tend to run into too much combat in this game at all. I'd say my combats have overall been on the easier side up to this point.

[Galithar]

Okay so I would definitely lean towards the higher side of CR. You want them to get beat up a bit, but then win. And you said you're okay with them dying if the dice say so IE lots of breath recharge and failed saves by them.

So Sorcerer has Con proficiency and a +3 so he will make the save way more often than the other two.

I would say as a quick off the cuff enemy. Take a Young Green Dragon, but give it the legendary actions and health of an adult dragon. So roughly 200 health.

That alone should let it stay in the fight a bit. I would also give it Legendary Resistance so they can't defeat it off a single failed save.

Edit: This would make the combat a little longer, without the full extra threat of an adult dragon. No boosts to the to-hit, which let's your Sorcerer and Artificer feel good about having a high AC. Most of them still don't have an amazing chance to save against a young Dragon breath attack. DC 14 if they are at a +2 means more than 50% failure. If you want to up the threat I would compromise between the adult and young DC and make it DC 16, but keep the Young 12d6 damage.

This leaves your BBEG as an above average Young Dragon. I didn't do the CR calculations, but I would estimate my changes would make it a 12ish CR. Legendary actions let it stand alone in combat, but it's damage output isn't boosted so it won't decimate the party round 1.

Just know it will be swingy. One high damage breath that hits all 3 with no saves will cripple them pretty hard.

[kingcheesepants]

Do they have resistance/immunity to poison? A dragon's biggest attack is the breath weapon and a green dragon's breath weapon is poison damage. If they can tank right through it due to resistance or immunity that's going to make things pretty easy but if they actually take full damage well that's a different story.

In either case though having some minions in the fight should be standard for any final boss. I'd give him a decent number of weak minions like kobolds and then a few middle minions like a low CR fiend (you said this dragon was using fiends earlier right) and one or two support types. Then it's all about tactics. The dragon should do flying hit and run breath weapon attacks, hide in his poison bog (he's a green dragon and should thus have some sort of poison bog to hide in). Have his allies attack and then grab the squishiest looking of the group and take him for a flight (then drop him after a while).

If you do end up giving the dragon a couple spells make them thematic and work with its strengths. Cloudkill or stinking cloud, darkness (to take advantage of his blindsight), charm person (or another similar effect to showcase his duplicitous and crafty nature) and maybe one or two others that make sense with how you've been portraying him up till now.

[DwarfFighter]

How about you use two (or even three!) young green dragons instead of a single monster? It's could be an interesting twist to find that the BBEG is in fact a pair of twins working together - or triplets!

-DF

[Borria]

Okay so I would definitely lean towards the higher side of CR. You want them to get beat up a bit, but then win. And you said you're okay with them dying if the dice say so IE lots of breath recharge and failed saves by them.

So Sorcerer has Con proficiency and a +3 so he will make the save way more often than the other two.

I would say as a quick off the cuff enemy. Take a Young Green Dragon, but give it the legendary actions and health of an adult dragon. So roughly 200 health.

That alone should let it stay in the fight a bit. I would also give it Legendary Resistance so they can't defeat it off a single failed save.

Edit: This would make the combat a little longer, without the full extra threat of an adult dragon. No boosts to the to-hit, which let's your Sorcerer and Artificer feel good about having a high AC. Most of them still don't have an amazing chance to save against a young Dragon breath attack. DC 14 if they are at a +2 means more than 50% failure. If you want to up the threat I would compromise between the adult and young DC and make it DC 16, but keep the Young 12d6 damage.

This leaves your BBEG as an above average Young Dragon. I didn't do the CR calculations, but I would estimate my changes would make it a 12ish CR. Legendary actions let it stand alone in combat, but it's damage output isn't boosted so it won't decimate the party round 1.

Just know it will be swingy. One high damage breath that hits all 3 with no saves will cripple them pretty hard.

Thanks a lot this is extremely helpful! I like the idea of the hp boost and a legendary resistance or 2, while still making my PCs decently hard to hit with normal melee attacks. I'll have to read up on the legendary actions that an adult green dragon can take. As for a swingy fight, I think that I'm alright with that and I'm not unwilling to fudge rolls if things end up poorly for them. Really though, they are opting into this fight by continuing to press for answers when they are already "heroes of the realm" who could retire in luxury if they wanted - if they wanted their characters to 100% live, they had their chance!

Do they have resistance/immunity to poison? A dragon's biggest attack is the breath weapon and a green dragon's breath weapon is poison damage. If they can tank right through it due to resistance or immunity that's going to make things pretty easy but if they actually take full damage well that's a different story.

In either case though having some minions in the fight should be standard for any final boss. I'd give him a decent number of weak minions like kobolds and then a few middle minions like a low CR fiend (you said this dragon was using fiends earlier right) and one or two support types. Then it's all about tactics. The dragon should do flying hit and run breath weapon attacks, hide in his poison bog (he's a green dragon and should thus have some sort of poison bog to hide in). Have his allies attack and then grab the squishiest looking of the group and take him for a flight (then drop him after a while).

If you do end up giving the dragon a couple spells make them thematic and work with its strengths. Cloudkill or stinking cloud, darkness (to take advantage of his blindsight), charm person (or another similar effect to showcase his duplicitous and crafty nature) and maybe one or two others that make sense with how you've been portraying him up till now.

None of these pcs are resistant or immune to poison. Also, I love these spell suggestions! This dragon has been using a lot of magic throughout the campaign, but most of it is bolstered by using a powerful focus. Having a bit of innate spellcasting that fits the theme (charm person is perfect for this) would keep him thematic and up the difficulty level.

How about you use two (or even three!) young green dragons instead of a single monster? It's could be an interesting twist to find that the BBEG is in fact a pair of twins working together - or triplets!

-DF

While I do really like this idea, I think running 2 dragons simultaneously in combat would be difficult for me and having multiple working together would create some plot holes the way I have the area surrounding the dragon set up currently. Definitely a thought for a cool set of enemies in another campaign though!

[Galithar]

Thanks a lot this is extremely helpful! I like the idea of the hp boost and a legendary resistance or 2, while still making my PCs decently hard to hit with normal melee attacks. I'll have to read up on the legendary actions that an adult green dragon can take. As for a swingy fight, I think that I'm alright with that and I'm not unwilling to fudge rolls if things end up poorly for them. Really though, they are opting into this fight by continuing to press for answers when they are already "heroes of the realm" who could retire in luxury if they wanted - if they wanted their characters to 100% live, they had their chance!



I love these spell suggestions! This dragon has been using a lot of magic throughout the campaign, but most of it is bolstered by using a powerful focus. Having a bit of innate spellcasting that fits the theme (charm person is perfect for this) would keep him thematic and up the difficulty level.

Legendary actions are basically this. They get 3 that refresh at the start if their turn. At the end of another creatures turn they can use any action.

For 1 action they can make a perception check to locate anyone if they are hiding.

For 1 action they can make a tail attack. This isn't in the young dragon stat block. I would make this a bite attack instead.

For 2 actions they can make a Wing Attack (attack added as a legendary action) you'll have to look it up, but it's basically an AoE that can knock PCs prone and then allows the dragon to move up to half its flying speed. Use the same DC for this that you use for its breath weapon whatever you decide on for that. (Or 1 higher to be true to the Stat block. Breath Attack DC is based on Con and Wing Attack is based on STR)

[J-H]

Customize your dragon. I like to give them a grab/throw effect on a successful bite attack (Athletics check to resist/negate).
Definitely give it some spellcasting, maybe several 1/days.

I like to let them cast a spell as a legendary action (costs 2 actions), so that they can still do a physical attack routine or a breath weapon.

Greater Invisibility is a great choice, but probably too powerful for your party. A few off-the-cuff suggestions: Blindness, Bestow Curse, Bane, Slow, Wall of Thorns.

[Unoriginal]

CR 8 means "3 lvl 9 PCs can handle 3 encounters like that in a day without breaking a sweat".


Question: do you want a solo boss fight, or would you be fine with the dragon having underlings fight alongside them?

[Borria]

Question: do you want a solo boss fight, or would you be fine with the dragon having underlings fight alongside them?

While I understand that balancing an encounter with only 1 enemy makes things harder because the PCs have such an advantage in terms of action economy, I'd really like to keep this encounter just the dragon vs them if at all possible. I suppose legendary actions are supposed to help with that as well.

[da newt]

Because your party is not very tactically savvy, I think Galithar's suggestions are right on track - create a young adult dragon (like a 20 yr old human = 100 yr old dragon).

I'd also ensure the lair was interesting (a lake, an elevated nook for hiding/sleeping, something to provide a bit of cover), and add a few spells - fog cloud, slow, stuff that makes everything harder but doesn't kill folks or use the MM Lair Actions, and remember that even a young adult green dragon is old (100 yrs) and smart (17 INT, 14 WIZ) - fight clever, they are planners.

In order to make it memorable / epic I'd ensure the dragon talked / taunted / threatened etc throughout.




An experienced party of 3 well built lvl 9 PCs should be able to handle a full adult.

[ImproperJustice]

Some considerations:

The Artificer and Druid can prepare and cast Prot from Poison which is a concentration free buff that lasts an hour and if they know they are fighting a Green Dragon, they will likely use.

Will the dragon be using a lair?

We fought a Green that had a lair made of a hedge maze. It was awful. He moved unhindered, closed passages, and could breathe through the walls at us.

If you wanna add a little challenge that could help.

[LumenPlacidum]

I'm sorry, can you suggest what are some likely spells that the players are likely to throw out and tactics they have previously employed? What are their "big guns" so to speak? The Sorcerer especially could have incredibly effective options or incredibly ineffective options. Do you want a straight slug-fest between them, or would you like the party to have to deal with disadvantageous terrain and circumstances (or advantageous ones)?

In general, big boss fights require the boss to have WAY more hitpoints than what the players fight otherwise, but not have that much greater offense than what the players fight normally. Throw in some abilities to force movement, knock down, and interrupt party combos, and you have a good boss. Dragons are actually a little harder to do this with, since they have very high damage on their breath weapons, typically. I would normally recommend not having a huge AC on a boss. Whatever is in the MM, either keep or lower by one. But, massively boost HP.

I suppose I could guess options based on what you've already said.

Level 9 moon druid. Let's say... upcast (level 5) Moonbeam for Con save (DC 17) 5d10 radiant damage followed by Wild Shape into an Ankylosaurus. Assume that each player is always in range to deal damage. The noise in this is where the noise in combat length will come from. If you went with an Adult Green Dragon straight out of the Monster Manual... it would have a 30% chance of failing the save against Moonbeam, meaning that the spell deals, on average, about 18 damage per round. The Ankylosaurus form has a 45% chance to hit, meaning that it will deal about another 9 points of damage. So, the druid is good for consistently 27 points of damage per round.

The level 9 armorer artificer. Let's assume... Haste held on himself. In truth, it seems likely that someone would try Hypnotic Pattern. Well, that's what Legendary Resistance is for, right? Anyway, that's four attacks with the gauntlets or homunculus. We'll just assume all the attacks are at the artificer's +11 to-hit and 1d8+7 damage. That's a 60% chance to hit each time, for an expected 31 damage per round.

The level 9 sorcerer is likely very swing-y. Against a dragon, you should assume they go full nova, holding nothing except escape in their back pocket. You say that the sorcerer likes to lightning bolt. Let's assume Empowered Lightning Bolt, upcast every round. That's a 10d6 lightning bolt with the ability to reroll low rolls. For a d6, that capacity isn't great. It's not even a +1 to damage per die. But, we'll assume it is just in case they have extra things that I don't know about. With a save DC of 18, the dragon is going to fail this save 55% of the time, making the sorcerer's damage output about 33 per round.

All together, you can expect your party to outlay an average of 90 damage per round at the beginning of the combat. That's average. If they all hit, then it's higher than that. So, your typical adult green dragon will last about 3 rounds against this party. It will use its poison breath once on average, and have two rounds of attacks. If the attacks are concentrated, then it might do an average of 50 damage or so to a player in a single turn, comparable to its average breath weapon damage. So, let's just assume the dragon does 50 damage per turn to a PC. On its breath turn, it spreads this damage out to do 50 to each PC. Now, I think you'll look at your character sheets and see that this is a huge chunk of their hitpoints to be doing each round. Through above average dragon tactics, this would certainly kill a PC. Through below-average tactics, you could make the party survive this and feel a harrowing, nail-biting victory against the numerical odds. Always attack the druid in wild shape. If the party is losing, have the dragon use Frightful Presence instead of Multiattacking. Lowering the breath damage to the Young dragon one is a good idea.

Actually, the suggestion to take the young dragon's offense and the adult dragon's defense (I would also maximize its hp per hitdie, but that's because I run for partly-optimized players), is a good one.

[noob]

- None of the players here are powergamers by any means. The sorcerer has only ever used their metamagic for spell slots or empowered spell and likes to lightning bolt things. The moon druid doesn't tend to wildshape.

This is in the first post.
Then people say "oh they are powergamers" and "the druid is going to be wild shaped in X" neither are true.
What happened is that they got some quite significant loot through gm generosity and whatever which makes them stronger than another average adventuring party.

[LumenPlacidum]

Yeah, but without any idea of what spells and tactics the party favors, we have to start somewhere regarding how to respond to the query.

Boss fights tend to be unsatisfying for two reasons: they end too quickly and feel anticlimactic, or they are mechanically overwhelming and the players really have no chance. Some estimate for how much damage the players put out is necessary to prevent the former. The latter is largely dealt with by ensuring that the boss cannot, in a single turn, outright kill a PC or drop all PCs. Dragons are dangerous especially for their ability to drop the entire party or most of the party in a breath weapon.

So, however you want to evaluate average damage done by the party, assume they use all the best abilities you've ever seen them use. Multiply the damage by about 5 or 6, to go for a combat lasting so many rounds. The combat will last longer than this most of the time (since you evaluated it using all their best abilities, which do run out eventually), or less than this if you failed to account for player options. In general, as long as the boss monster is making its presence known (by dealing damage, sure, but also by tossing players around, knocking them down, and changing the parameters of the battlefield), you won't have a problem with the fight being too long.

Then, as long as the boss monster doesn't put out so much damage that the fight is going to overwhelm the players very quickly, you won't have a danger in the boss steamrolling the players.

Practically anything in between is fair game. The fine-tuning of such a fight comes from having the boss pressure the players' defensive resources JUST ENOUGH that they get to the point where they have to use their defensive abilities just to stay alive. Bards using cutting words, casters using shield, druids being knocked out of wild shape, fighters being down to 3 hp, et al. At that point, the party feels desperate (which is where a lot of the fun of fighting a big boss comes from). Then, you get to just spread out the boss's attention to tone the boss down. Use tactics that seem especially dire but which are highly telegraphed and avoidable if the party gets down to the point where they're running on empty. The dragon might fly up to the roof of its lair and start to pull on a massive weakened section of the roof. Tell the party that in the next turn, the dragon is going to try to pry the section of ceiling out, which will certainly crush most of them to death. This sounds profoundly unfair, but it actually represents giving the party a breather. They don't have to deal with the hitpoint-race for those turns. They might just have to enact their mobility to avoid the attack. Or, they could distract it, or give it disadvantage on strength checks or something.

It is much, much easier to have a powerful enemy do inefficient things to keep the party alive than it is having a low-powered enemy seem to provide more challenge than its mechanics would suggest.

So, ultimately my advice was: dial up the boss's survivability a lot, but mostly through HP rather than action-denial like AC (but also including more legendary resistances, counterspells, immunities, whatever) and dial down the boss's offensive output. One thing that could be done is to have the dragon do less breath damage, but let its breath recharge more often. Then you can press on the party's resources and also not immediately overwhelm them.

[Borria]

Thank you everyone for the replies, sorry I've been off the thread for a few days!

Some considerations:

The Artificer and Druid can prepare and cast Prot from Poison which is a concentration free buff that lasts an hour and if they know they are fighting a Green Dragon, they will likely use.

Will the dragon be using a lair?

If you wanna add a little challenge that could help.

Though it's still possible they find out in advance what they'll be fighting, it seems extremely unlikely to me so they probably won't know to cast that in advance. See below with regards to the lair.

I'm sorry, can you suggest what are some likely spells that the players are likely to throw out and tactics they have previously employed? What are their "big guns" so to speak? The Sorcerer especially could have incredibly effective options or incredibly ineffective options. Do you want a straight slug-fest between them, or would you like the party to have to deal with disadvantageous terrain and circumstances (or advantageous ones)?

As I mentioned, the sorcerer tends to lead with lightning bolts and use empowered spell to buff them up. The sorcerer also likes fireball, but has been fighting a lot of devils recently so has stayed away from fire damage spells for a while. The artificer usually is wearing the heavy armor, and chooses to stay close and use the thunder gauntlets to protect teammates. Honestly, that character hasn't cast much in combat besides a fey-touched misty step to reposition. My druid likes to upcast thunderwave, shatter, and moonbeam and when she does wildshape, she usually becomes a Deinonychus or a giant constrictor snake. The fight will likely be in the dragon's lair, though due to the world's lore the dragon (and the ones before him that occupied this lair) have not been under serious threat for over 1000 years, so it would make sense if the terrain of the lair doesn't provide too big of an advantage in combat.

[LumenPlacidum]

As I mentioned, the sorcerer tends to lead with lightning bolts and use empowered spell to buff them up. The sorcerer also likes fireball, but has been fighting a lot of devils recently so has stayed away from fire damage spells for a while. The artificer usually is wearing the heavy armor, and chooses to stay close and use the thunder gauntlets to protect teammates. Honestly, that character hasn't cast much in combat besides a fey-touched misty step to reposition. My druid likes to upcast thunderwave, shatter, and moonbeam and when she does wildshape, she usually becomes a Deinonychus or a giant constrictor snake. The fight will likely be in the dragon's lair, though due to the world's lore the dragon (and the ones before him that occupied this lair) have not been under serious threat for over 1000 years, so it would make sense if the terrain of the lair doesn't provide too big of an advantage in combat.

So, the druid is good for about 33 damage per round if the upcast level 5 moonbeem is concentrated upon and followed by a bunch of upcast shatters/thunderwaves (level 4).

If the Artificer isn't self-buffing before wading into combat, that downgrades his expected damage per round to about 24. Or, even less if they aren't using a bonus action to do damage through a homunculus or two-weapon fighting or something.

These things come together for about the same estimate I gave before of around 90 damage per round. Better choices by the artificer could improve that.

As such, if you want the battle to last at least 3 rounds, then 270 hp backed by an AC of 19 will probably get you that.

Are you saying that the dragon is likely overconfident because of its long tenure of safety? In that case, put it into melee combat more instead of favoring its breath weapon. It will make the dragon less effective at wiping the party. However, if the dragon focuses its attacks even after a PC goes down, the dragon in melee becomes more effective at killing a PC.

That said, the dragon is still smart. If the artificer is invoking disadvantage on attack rolls against other PCs and their own AC is super-high, then the dragon should probably decide to use saving throw abilities instead of attack rolls, and the breath weapon comes back into play?

Perhaps the best thing the dragon can do to make the players realize just how powerful it is is to use the wing attack legendary action. Reposition away from the artificer and knock a bunch of people down, dealing some damage. Use it a lot! It's a great ability for drawing out a fight and players who get tossed around feel like they're fighting something massive. In fact, by frustrating the artificer's melee dependency, you might even draw out better tactical presence from the player.