D&D 5E Balancing Mummy Lord fight with CR

[DurrandDurr]

I have a party of 4, level 13 players. One is a Paladin who has an aura that prevents being frightened as well as a +1 Sword. Two characters can do fire damage. The rest of the party is a Druid, Sorcerer, and Bard. They wipe out solo monsters quickly; and use Banishment. The Paladin did about 80 points of damage in one attack on a nat. 20, and two of the party members can cast fire-based attacks. I think the Mummy Lord wouldn't last more than 2 rounds solo.

I'm thinking of giving the Mummy gold-plate armor that is fused to the mummy's body that grants fire resistance (removing the fire vulnerability), but adds vulnerability to lightning (gold is conductive) to counter meta-gaming knowledge. That might let it last a couple more rounds.

Adding more monsters to this fight seems best, but not sure how many to add or what type Thematically I was considering regular mummies, an Air Elemental or a couple undead constrictor snakes (looking like Bone Naga but without the lore). Would 2-4 more mummies do it, or is that overkill?

 

[CleverNickName]

I'd give it a spell reflection item, but I don't want it to fall into the hands of the players.

Easy. The "spell reflection item" is a magical tattoo on the palm of its left hand. It turns to dust when the party vanquishes it.

 

[iserith]

The bulk of the map is difficult terrain: beach-like sand and fallen rocks. I was trying to think of a sand tentacle effect (Black Tentacles) in the center of the chamber. Or a whirlpool of sand that drags them down (quicksand rules?). I'm a new DM so creating these environmental things is a learning curve.

Consider some way to get her above the ground like on elevated platforms, maybe supported by ruined pillars or whatever. That'll provide cover - possibly total cover if prone - and slow down the melee PCs from getting to her.

Max out HP as well.

 

[CleverNickName]

In my experience, the Mummy Lord as-written in the MM plays more like a CR 10 or CR 12 monster. So yeah, I think adding a handful of Deathlocks in the mix won't be too bad. Remember that the Deathlocks are there for support. Save their spell slots for Counterspell and Dispel Magic, and have them stick to Eldritch Blast from a distance (and focus fire on that paladin).

But remember that the goal is to make the battle exciting, but winnable. You don't want to completely obliterate the party, and you don't want your villain to be disposable. Does your Mummy Lord have an escape plan?

 

[jgsugden]

Consider a storyline in which they don't want to kill it. When they kill it, something really bad happens unless they achieve something first. Maybe it has knowledge. Maybe it is a 'cork in the bottle' keeping a great evil at bay. Maybe it the corrupted form of a hero, and the PCs have been asked to help contain it so that the soul can be returned.

Consider giving it alternative spells. Phantasmal Force, when used correctly, can massively change a scenario. So can modify memory. If it has Major Image as a 3trd level spell, there could be hundreds of permanent illusions in the lair, creating massive confusion about what is real, what isn't etc... Domination, Enemies Abound, etc...

Consider that if it can cast divination, if any undead in the lair can sense anything living within 120 feet almost constantly, etc... that it will be nearly impossible for the PCs to sneak up on it, but it may know exactly where the PCs are at any given time. If so, it can set off traps from great distances. If you need ideas, Google Grimtooth's Traps. A 300 foot vertical shaft with a 2 ton boulder suspended from the top in an easily severable manner...

Consider having the heart of the lair actually be on another plane and thus changing the usual rules of combat dramatically. Moving it to the Astral Plane, or into Ravenloft ... or a Demiplane with unique properties.

Consider that perhaps the Mummy Lord isn't the real threat ... but is the gatekeeper of the real threat.

 

[Stalker0]

In my experience, the Mummy Lord as-written in the MM plays more like a CR 10 or CR 12 monster.

So i was curious and took a look at the CR calculator. If you assume players have magic weapons.....the defensive CR is only 6, 7 if it has shield of faith already up. No wonder this thing drops so quickly.

 

[DurrandDurr]

So i was curious and took a look at the CR calculator. If you assume players have magic weapons.....the defensive CR is only 6, 7 if it has shield of faith already up. No wonder this thing drops so quickly.

Which CR calculator are you using? 5etools/calculator? DMG?

 

[J-H]

I'd make it one Mummy Lord, one Simulacrum Mummy Lord, 3 regular mummies, and a couple of earth elementals or something, if you want to make it a tough fight. The mummy lord is SO SQUISHY.

Also, change the default spell list around. Have the Mummy Lord(s) Counterspell every leveled spell they can. Pre-load the battle area with Spiritual Guardians for some guaranteed damage. Use Sand Form to stay out of melee.

 

[Stalker0]

Which CR calculator are you using? 5etools/calculator? DMG?

5e tools.

 

[Eltab]

For variety, instead of putting the PCs on the floor and the Mummy up on a pillar / balcony / whatever, reverse the scene: the PCs finally pry a stone trap door out of the floor, and see the Mummy Lord's sanctum area below.

Inspiration to the first player to quote Indiana Jones: "Snakes. Why did it have to be snakes?" (No there are no snakes ... this time.)

Then the PCs get to figure out how to get down there (besides falling / jumping and taking the damage) as the defenders arrive and begin doing their thing.

 

[Flamestrike]

I have a party of 4, level 13 players. One is a Paladin who has an aura that prevents being frightened as well as a +1 Sword. Two characters can do fire damage. The rest of the party is a Druid, Sorcerer, and Bard. They wipe out solo monsters quickly; and use Banishment. The Paladin did about 80 points of damage in one attack on a nat. 20, and two of the party members can cast fire-based attacks. I think the Mummy Lord wouldn't last more than 2 rounds solo.

I'm thinking of giving the Mummy gold-plate armor that is fused to the mummy's body that grants fire resistance (removing the fire vulnerability), but adds vulnerability to lightning (gold is conductive) to counter meta-gaming knowledge. That might let it last a couple more rounds.

Adding more monsters to this fight seems best, but not sure how many to add or what type Thematically I was considering regular mummies, an Air Elemental or a couple undead constrictor snakes (looking like Bone Naga but without the lore). Would 2-4 more mummies do it, or is that overkill?

Dude, firstly you're probably doing CR wrong, in that you're using it as a guideline for overall encounter difficulty (when it's not).

For example, a CR15 Mummy Lord is only a Medium encounter for 4 x 13th level PCs, even within the scope of a standard adventuring day (it only chews up 13,000 of roughly 54,000 XP for 4 x 13ths between a single long rest).

Meaning you could literally throw 4 separate Mummy Lord encounters at this party in a single day (to fill in the encounter budget for the adventuring day), and they should be just fine.

A Medium encounter is this:

Medium. A medium encounter usually has one or two scary moments for the players, but the characters should emerge victorious with no casualties. One or more of them might need to use healing resources.

At that XP budget, the PCs are expected to win, with no casualties, and only 1 or 2 of them MIGHT need to use healing resources after the battle.

Adding to this is the fact your PCs have magic items (and those items are not included in the base games math) so you should expect them to steamroll this encounter.

Personally I would do the following:

Give the Mummy Lord the following (cursed, because Mummy) magic items: Bracers of Armor, Ring of Fire resistance, Ring of protection. This gives it AC 20, and resistance to Fire (cancelling out its vulnerability). Curse those items with something nasty to anyone foolish enough who attempts to attune to them that isnt the Mummy.

Give the Mummy Lord Spirit Guardians on its spell list. Cast it using a 5th level slot ASAP (before the battle if possible - remember the Mummy has Divination so it knows the PCs are coming). The Mummys other 5th level slot should be used on Spiritual weapon (bonus action) plus an action of your choice on round 1, and a 6th level Harm the following round.

Add 7HD to the Mummy Lord, bringing its total HP up to around 150. Increase its Wisdom to 20 and add +1 to every single Save DC it has (spellcasting and special abilities, plus wisdom based skills and saves).

Those changes increase its CR by 1 to CR 16 and 15,000 XP.

Now add 4 Mummy mooks (AC 15 from their bronzed armor). For flavor, change the weapons to Bronze greatswords (damage stays the same, but is now slashing and necrotic). This adds 2,800 XP to the encounter, pushing it into Hard territory, but shouldn't multiply the difficulty due to the low CR (CR 3) of the Mummies any more than roughly 1.5 (treat the mooks as a single monster).

The total encounter budget is now around roughly 25,000 pushing it into Deadly for that party (and now using roughly 1/2 of that days encounter budget).