Level 20 Full Encounter

[Nagog]

Howdy Playgrounders!

I've been running a level 20 campaign for a few sessions, and while it is a BLAST, I have found it takes a LOT more effort to prepare fun and challenging combat encounters. That said, if you know who Sitka of Davenport is, stop here and wait until our next session.

SO: I need help brainstorming a challenging encounter for a party of 6 level 20 PCs. Currently the encounter consists of the former Archdevil Moloch (who in this continuity has power over bloodlines, ancestry, and the like). The setting is the Hoard of the Greatwyrm Ashardalon at the Bastion of Unborn Souls. Ashardalon himself is MIA (Presumed dead) The party previously fought and "killed" a Mummy Lord who had a lair full of Brown Mold and Lava and a puzzle to figure out his conditional damage immunity. After how in-depth that encounter was (with a battle map that included lava hazards, flameskulls causing huge bursts of Brown Mold, and lair actions that created new hazards and restricted mobility options) I could use some ideas on how to make this one just as immersive.

Here's what I've got so far:

The Treasure Hoard has mimics in it
Moloch can summon other fiends (probably Demons because Demon Lords have more stat blocks than Archdevils) and/or borrow some interesting Demon lord abilities
Give Moloch a bunch of magic items (ala Cube of Force, Amulet of Pure Evil, etc.) from the Hoard (which means the party will claim it after the combat)

What are some ideas ya'll have to spice up this combat?

[Sorinth]

Presenting a moral dilemma where the focus is on saving something/someone rather then fighting could be fitting component to a devil fight.

Something that shifts all/some of the damage done to Moloch to prisoner(s) could be interesting. If they want to save the prisoner(s) then they can't just wail away on Moloch, they first need to break/suppress that magical bond/free the prisoner(s) before they can freely go after Moloch. So some PCs focus on dealing with the minions, while some work on the rescue. If there are several prisoners then each one could be providing Moloch with a unique power, so freeing them also prevents that power from being used and/or weakens Moloch.

[CTurbo]

Ok hear me out......

SEVEN million Kobolds! lol

I've never had the pleasure of being a part of any 20th level campaign/encounter, but I imagine it is difficult to provide a challenge to a party especially with 6 people. I would probably build some super buffed character enemies with legendary resistances for them to go up against, and even though the seven million kobolds was a joke, I do think a mass invasion encounter would be fun albeit hard to run. Imagine a near infinite amount of Gnolls and/or Orcs invading one of the party's favorite towns. The party has to figure out where they're coming from and stop them. The numbers would have to be overwhelming. Not sure how I'd handle it. A Swarm of Orcs? blocks of 20? I'm also not sure what the source would be. Maybe a simple teleportation circle? Maybe a crack in some new plane of existence that you just made up?

[Dalinar]

Currently the encounter consists of the former Archdevil Moloch (who in this continuity has power over bloodlines, ancestry, and the like).

I think this is kind of the key. In my mind, when you're talking about an archdevil, even a former one, you really want to sell how evil and cruel someone like that can be, right? If Moloch (always a fun name to invoke) is in charge of blood relationships, then this is the time to really hit the PCs in the backstory.

You don't describe the PCs here, so I'm going to spitball based on a few adventurer stereotypes.

Is one of the characters an orphan? Hit 'em with some kind of phantasm, and describe their missing parents calling them home while the party watches them act out their response in horror. They then have to fight the PC's mom. Twenty of her, in fact. Play up the disturbing trippy side of it. (Use whatever stat block you think would be appropriate for such an encounter--I'm not super familiar with the stock 5e monsters. There's probably an appropriate undead?)

Is one of the characters out for revenge after a loved one was murdered? Turns out (according to Moloch) that person actually hated their guts and was glad to have died because it meant they didn't have to tolerate the PC anymore. This can lead into something similar to the above, where it's an effigy of someone related the PC has to fight. In this case it's a better setup for a two-monster encounter: one representing the dead loved one, and another representing the character who wronged the PC.

Is one of the characters really proud of their country of origin? Have them witness some war crimes. They were Moloch's idea in the first place, after all--have him tell the PC in question how much he enjoyed the screams, and how glad he is that the PC seems to enjoy his "art." This can lead into an encounter where the PCs have to save some NPCs while other NPCs attack them--and each failure to save the NPC is maybe a save against psychic damage for the whole party, or something to that effect.

(This may be a good time to remember to double check where your players' personal boundaries are.)

Does somebody have a Warlock patron? Might be a good time for Moloch to air out some of the patron's dirty laundry. Bonus points if it's a Celestial warlock. This one's gonna depend a lot on the nature of the warlock-patron relationship.

So you can craft some phases to the encounter out of those sorts of ideas.

Eventually it'll be time for Moloch himself to be the one dishing out blows. You have the thing with Ashardalon's hoard already, which is great. Maybe double down and give Moloch some dragon-like qualities? Claw and tail attacks, a breath weapon, a fear effect, stuff like that. If he's got descendants/ancestors of his own, now's the time to call that up.

As a player, a big thing in my experience that's made some of my DM's most memorable encounters was hitting the PCs in ways they don't expect. Last session we fought some guys who were able to apply a permanent penalty to our random encounter dice, for instance. Draining resources like spell slots or hit dice is another fun one (with extra badness if the player doesn't have any). In Moloch's case, you probably want to stick to the bloodline theme, so perhaps force some cruel choices related to that. In my mind I'm imagining Moloch inflicting you with a deadly disease with a twist--you can choose to have it affect a blood relative of yours instead of yourself, negating Moloch's attack but betraying someone you're probably close to in the process. (Might be extra fun if one of the PCs has a real bad relationship with a relative and then tries to get Moloch to use it on them!)

Hopefully something up here will get the gears turning! The main thing in my mind is to just try to be cruel--your players will enjoy it more if they get to viscerally hate the baddie by the end of the session, and as a (former) archdevil, you'll never get a better opportunity.

[Oramac]

In my experience, the number one thing that makes an encounter of any level memorable is movement. Sitting in one spot for 10 rounds and smacking a big bag o' hit points gets old really fast.

So with that, I will often include elements of movement in a fight. Lair Actions that force movement, Legendary Actions that move, a bunch of minions running around shoving/grappling/throwing and causing chaos.

But above all: TERRAIN movement. Especially movement that affects both the party AND the bad guys. Waves crashing over a ship; earthquakes shifting the terrain; even just heavy rain making it all super slippery.

For your specific encounter, since Ashardalon is MIA, but we're in his Hoard, surely there's traps and such that even Moloch does not know about. Even better if it's a Thunderwave trap that forces movement when triggered (or something of that sort). Also, changing the location too. Perhaps this hoard is merely an illusion. Using XYZ thing causes the hoard to explode. This causes damage to both the party and enemies, but more importantly, it shatters the ground and everyone falls into the TRUE hoard in a cavern below.

Basically, anything that causes a change in the environment is bound to be memorable.

[JonBeowulf]

Ok hear me out......

SEVEN million Kobolds! lol

I've never had the pleasure of being a part of any 20th level campaign/encounter, but I imagine it is difficult to provide a challenge to a party especially with 6 people. I would probably build some super buffed character enemies with legendary resistances for them to go up against, and even though the seven million kobolds was a joke, I do think a mass invasion encounter would be fun albeit hard to run. Imagine a near infinite amount of Gnolls and/or Orcs invading one of the party's favorite towns. The party has to figure out where they're coming from and stop them. The numbers would have to be overwhelming. Not sure how I'd handle it. A Swarm of Orcs? blocks of 20? I'm also not sure what the source would be. Maybe a simple teleportation circle? Maybe a crack in some new plane of existence that you just made up?

So... Moria.

[Nagog]

I think this is kind of the key. In my mind, when you're talking about an archdevil, even a former one, you really want to sell how evil and cruel someone like that can be, right? If Moloch (always a fun name to invoke) is in charge of blood relationships, then this is the time to really hit the PCs in the backstory.

You don't describe the PCs here, so I'm going to spitball based on a few adventurer stereotypes.

Is one of the characters an orphan? Hit 'em with some kind of phantasm, and describe their missing parents calling them home while the party watches them act out their response in horror. They then have to fight the PC's mom. Twenty of her, in fact. Play up the disturbing trippy side of it. (Use whatever stat block you think would be appropriate for such an encounter--I'm not super familiar with the stock 5e monsters. There's probably an appropriate undead?)

Is one of the characters out for revenge after a loved one was murdered? Turns out (according to Moloch) that person actually hated their guts and was glad to have died because it meant they didn't have to tolerate the PC anymore. This can lead into something similar to the above, where it's an effigy of someone related the PC has to fight. In this case it's a better setup for a two-monster encounter: one representing the dead loved one, and another representing the character who wronged the PC.

Is one of the characters really proud of their country of origin? Have them witness some war crimes. They were Moloch's idea in the first place, after all--have him tell the PC in question how much he enjoyed the screams, and how glad he is that the PC seems to enjoy his "art." This can lead into an encounter where the PCs have to save some NPCs while other NPCs attack them--and each failure to save the NPC is maybe a save against psychic damage for the whole party, or something to that effect.

(This may be a good time to remember to double check where your players' personal boundaries are.)

Does somebody have a Warlock patron? Might be a good time for Moloch to air out some of the patron's dirty laundry. Bonus points if it's a Celestial warlock. This one's gonna depend a lot on the nature of the warlock-patron relationship.

So you can craft some phases to the encounter out of those sorts of ideas.

Eventually it'll be time for Moloch himself to be the one dishing out blows. You have the thing with Ashardalon's hoard already, which is great. Maybe double down and give Moloch some dragon-like qualities? Claw and tail attacks, a breath weapon, a fear effect, stuff like that. If he's got descendants/ancestors of his own, now's the time to call that up.

As a player, a big thing in my experience that's made some of my DM's most memorable encounters was hitting the PCs in ways they don't expect. Last session we fought some guys who were able to apply a permanent penalty to our random encounter dice, for instance. Draining resources like spell slots or hit dice is another fun one (with extra badness if the player doesn't have any). In Moloch's case, you probably want to stick to the bloodline theme, so perhaps force some cruel choices related to that. In my mind I'm imagining Moloch inflicting you with a deadly disease with a twist--you can choose to have it affect a blood relative of yours instead of yourself, negating Moloch's attack but betraying someone you're probably close to in the process. (Might be extra fun if one of the PCs has a real bad relationship with a relative and then tries to get Moloch to use it on them!)

Hopefully something up here will get the gears turning! The main thing in my mind is to just try to be cruel--your players will enjoy it more if they get to viscerally hate the baddie by the end of the session, and as a (former) archdevil, you'll never get a better opportunity.

I like this one a LOT. He's one of three dads of the Tiefling Warlock in the party (bio dad made a deal with Moloch, hence the PC is a Tiefling, then when bio dad kicked him and mom out and pinned the Fiendish influence on mom, Dad #3 is a unicorn who became his Celestial Patron), so there is a LOT to work with there. Another PC is a dad and his kid has been an active player in previous campaigns, so he is on the table for manipulation. Another PC had her found family slaughtered in front of her, so while not related by blood, he may be able to convince her that he could fix that (whether or not he can isn't relevant if he doesn't plan to deliver). This has so much potential!

In my experience, the number one thing that makes an encounter of any level memorable is movement. Sitting in one spot for 10 rounds and smacking a big bag o' hit points gets old really fast.

So with that, I will often include elements of movement in a fight. Lair Actions that force movement, Legendary Actions that move, a bunch of minions running around shoving/grappling/throwing and causing chaos.

But above all: TERRAIN movement. Especially movement that affects both the party AND the bad guys. Waves crashing over a ship; earthquakes shifting the terrain; even just heavy rain making it all super slippery.

For your specific encounter, since Ashardalon is MIA, but we're in his Hoard, surely there's traps and such that even Moloch does not know about. Even better if it's a Thunderwave trap that forces movement when triggered (or something of that sort). Also, changing the location too. Perhaps this hoard is merely an illusion. Using XYZ thing causes the hoard to explode. This causes damage to both the party and enemies, but more importantly, it shatters the ground and everyone falls into the TRUE hoard in a cavern below.

Basically, anything that causes a change in the environment is bound to be memorable.

Since making this post, I've done a bit of research into the fluidity of gold coins (thank heavens for Scrooge McDuck setting a precedent for people asking "can you swim in gold coins", amirite?), and found that it's fairly easy to get buried in coins if there's enough of them and they're small enough (I'm using large glitter to portray the gold on a battlemap so getting covered in it is not just in-game unfortunately).
Also if a large enough creature stirs up the gold, it can act as a fluid! So Moloch may just call in a Kraken or something of that size and nature, and whenever it moves it shifts the battlemap in it's wake.

[Oramac]

glitter

Die, heathen.

But in all seriousness. That will absolutely be memorable!