Balancing monster syngergies

[ZenBear]

So my players are running through the Lost Mine of Phandelver with some modifications, and up next for them is the Ruins of Thundertree. Normally players would be facing a Young Green Dragon (https://roll20.net/compendium/dnd5e/Young%20Green%20Dragon#content) (CR 8) in a tower in the town, but that doesn't fit the lore of my homebrew setting so I'm doubling down on the malignant vegetation vibe of Thundertree and placing a Shambling Mound (https://roll20.net/compendium/dnd5e/Shambling%20Mound#content) (CR 5) instead. The question I have is how dangerous this thing will be to my party.

My party consists of a melee fighter with a longsword and hand crossbow (pistol), a melee rogue, a melee paladin, and two spellcasters (Wiz/War) with ranged cantrips. They are all level 3 and have a bonus feat that I gave them at level 1. The creature will be sitting at the top of the tower, so I don't expect them to be able to plink away at range unless they bait it down and kite it. In the standard LMoP the dragon flees once it hits half health, but I don't think a Shambling Mound would do the same thing. It's feasible that the party could kill this guy quite handily, or maybe they'll get killed. I'm uncertain and a bit worried.

I also want to know how much you think it would increase the CR of the encounter if I were to add two to three Will o' Wisps (https://roll20.net/compendium/dnd5e/Will-o'-Wisp#content) (CR 2) that buzz around and heal it with lightning attacks or finish of downed enemies with Consume Life. I don't intend to do this to my players because they're new and they'd take it pretty hard if their characters died, but it's a very fun and powerful monster synergy that I want to have available for a mega-dungeon that I'm designing on the side. In that game the players would either play as Revenants ala Dark Souls or just keep rolling up a roster of new characters ala Darkest Dungeon.

[McSkrag]

So my players are running through the Lost Mine of Phandelver with some modifications, and up next for them is the Ruins of Thundertree. Normally players would be facing a Young Green Dragon (https://roll20.net/compendium/dnd5e/Young%20Green%20Dragon#content) (CR 8) in a tower in the town, but that doesn't fit the lore of my homebrew setting so I'm doubling down on the malignant vegetation vibe of Thundertree and placing a Shambling Mound (https://roll20.net/compendium/dnd5e/Shambling%20Mound#content) (CR 5) instead. The question I have is how dangerous this thing will be to my party.

My party consists of a melee fighter with a longsword and hand crossbow (pistol), a melee rogue, a melee paladin, and two spellcasters (Wiz/War) with ranged cantrips. They are all level 3 and have a bonus feat that I gave them at level 1. The creature will be sitting at the top of the tower, so I don't expect them to be able to plink away at range unless they bait it down and kite it. In the standard LMoP the dragon flees once it hits half health, but I don't think a Shambling Mound would do the same thing. It's feasible that the party could kill this guy quite handily, or maybe they'll get killed. I'm uncertain and a bit worried.

I also want to know how much you think it would increase the CR of the encounter if I were to add two to three Will o' Wisps (https://roll20.net/compendium/dnd5e/Will-o'-Wisp#content) (CR 2) that buzz around and heal it with lightning attacks or finish of downed enemies with Consume Life. I don't intend to do this to my players because they're new and they'd take it pretty hard if their characters died, but it's a very fun and powerful monster synergy that I want to have available for a mega-dungeon that I'm designing on the side. In that game the players would either play as Revenants ala Dark Souls or just keep rolling up a roster of new characters ala Darkest Dungeon.

Man I love the Shambling Mound + Will-o'-Wisp idea. Sounds fun and really fits the Thundertree concept.

The short answer is I think it's a good tough encounter.

I'm also currently running a set of 6 new D&D players through LMoP with a few homebrew mods to the campaign as well. (On a sidenote everyone is loving the LMoP and having a great time)

I think if you look at the total attacks, overall average damage, and HP of the party vs. the monsters they seem fairly even.

If the Shambling Mound engulfs a PC it could easily kill them.

The Will-o'-Wisps are going to be tough to take out with a 19 AC and all the resistances and immunities. I agree about avoiding any permadeaths with the Consume Life.

If the party goes into the encounter wounded and low on spells it could be very difficult.

Overall I really like it.

[SirGraystone]

It's very good idea (I may well steal it) but yes very dangerous for a group of level 3, but to make it somewhat easier you could:

- Have the Will-o-Wisp only heal the shambling mount unless the players attack one and even them only have the attacked one fight back
- Lower their AC to 17
- Have then turn invisible and run away if they lose half their hp
- Or have the Will-O-Wisp fight the players by themselves then run off when hurt not turning invisible so the players can follow and leads them to the Shambling Mound.

[Man_Over_Game]

It's worth noting that the Green Dragon isn't really supposed to be killed but simply driven off. The Dragon has a reliable way of fleeing with his flight, but the Shambling Mound is a lot less mobile and might have less reason to flee.

Keep that in mind during this fight.

[Afrodactyl]

Will o' wisps and shambling mounds are a pretty tough fight, especially for a level three party.

I would personally nerf the wisps and the mound into the dirt if I were going to use it in LMoP

[GlenSmash!]

A Shambling Mound that fights to the death seems a suitable replacement for a Young Green Dragon that flees.

[Man_Over_Game]

A Shambling Mound that fights to the death seems a suitable replacement for a Young Green Dragon that flees.

+2 WillOWisps healers.

[GlenSmash!]

+2 WillOWisps healers.

That seems a bit much for me, I would probably use lower AC plant monsters like Twig Blights to fill out the encounter, but admittedly I haven't run LMoP for 6 players.

[ZenBear]

Thanks for the feedback everyone! I’m glad people like the combo, I thought it was quite clever and thematic. 😋 To reiterate my OP, I don’t intend to have the level 3 party fight the Mound and Wisps unless I decide to have the Wisps draw the Mound away once it reaches half health in an effort to keep it safe. I’m setting up a larger threat for the party to discover, and the Mound, Blights and Wisps are minor pieces in a much more dangerous game.

So by itself, the Shambling Mound would be a difficult fight but not necessarily lethal? I should note that both casters specialize in illusions, so they’re not optimized blasters.

[McSkrag]

That seems a bit much for me, I would probably use lower AC plant monsters like Twig Blights to fill out the encounter, but admittedly I haven't run LMoP for 6 players.

Yeah, thinking about it again I agree the Will-o'-wisps are probably too dangerous with the high AC and all the resistances/immunities. I would nerf them with lower AC and HP and then have them heal or attack depending on how the battle is going.

[McSkrag]

I don’t intend to have the level 3 party fight the Mound and Wisps unless I decide to have the Wisps draw the Mound away once it reaches half health in an effort to keep it safe.

Good call. That gives you flexibility to adjust the difficulty as you go.


I’m setting up a larger threat for the party to discover, and the Mound, Blights and Wisps are minor pieces in a much more dangerous game.

Muhahaahahaha!


So by itself, the Shambling Mound would be a difficult fight but not necessarily lethal? I should note that both casters specialize in illusions, so they’re not optimized blasters.

I think the Shambling Mound on it's own will be a good tough fight, but the party should be able to handle it with decent tactics.

Roughing out the numbers: I assume the casters at least have an attack cantrip like Firebolt or Eldritch Blast? With an average +5 attack vs. the Mound's 15 AC the party will hit 50% of the time for ~10 damage hit which gives them ~25 damage per round. They will need to up that damage somehow to kill it before the Mound engulfs someone.

The Mound has +7 attack x2 which will hit AC 17 50% of the time for 13 damage. So it should average 13 damage a round. Each PC can get hit 2-3 times before getting knocked out. Then if it hits the same PC twice (~25% chance each round) they are grappled and Engulfed if the fail a DC 14 STR check. If a PC gets engulfed early in the fight they could get smoked.

Seems like a good tough fight which will require good tactics and teamwork by the party.

[ZenBear]

Sorry to necro this thread, but I figured this would be the most sensible place to update. I ran my players through Thundertree and replaced the Young Green Dragon with a Shambling Mound and one Will o’ Wisp. My party was level 3 with a bonus feat granted at creation consisting of a Battlemaster Fighter, Illusionist Wizard, Raven Queen Warlock, Thief Rogue and Oath of the Waifu Paladin. The party snuck up to the tower through the aid of their illusions and every character having decent Dex, and the Warlock snuck up to the top of it with the Wizard’s Invisibility spell. The floor was covered in dense foliage (the Shambling Mound) and the Wisp was invisible as well. As the Warlock attempted to cross the room to investigate a chest, the Mound attacked. It rolled a nat 1 and the lock escaped back down the stairwell.

The Fighter charged the doorway to tank as the Mound followed down, and the Rogue backed him up. The Wizard is a fire genasi with the Elemental Adept feat taken as his bonus at lvl 1, so when he started blasting away with Burning Hands and Firebolt he was still doing full damage. To my great surprise, the Mound (which rolled 3 nat 1’s over the course of the combat) failed to down any of the party, though the Fighter came dangerously close and was Engulfed in the round prior to the Mound’s death. The Wisp got involved by healing the Mound with its lightning attack, but was caught in an upcast Burning Hands and shot down by the Warlock as it tried to flee, despite being invisible (nat 20 Perception and double 18’s on disadvantage attack ftw). Through most of the fight the Paladin focused on healing as she is built to do incredibly well, but after her senpai the Rogue got slapped she went ham with a Smite and finished off the Mound in spectacular fashion!

I know things could have gone much worse had I not rolled so poorly, but it still surprised me how well a 3rd level unoptimized party handled this encounter so tidily.