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?

 

[Stalker0]

The math does not account for Magic items, so those need to be taken into account by the DM when doing his encounters and figuring difficulty (like everything else).

Agreed. I just think that WOTC underestimated how many groups are going to have access to at least basic +1 weapons at the 10+ level range, and how it just completely changes the durability of the monster when they do. Or maybe I am the special snowflake and most groups really do not have magic swords and such by 10th level, but even looking at their own treasure tables that doesn't seem to be the default assumption. As a consequence I think many of their monsters are completely over CRed compared to the "default" party in actual play.

Aka, I really think CR's should just assume magic weapons past a certain CR, and then give special notes if you don't have them. Similar to how flying + ranged damage is no longer a CR booster at CR10+, because its assumed a party of those levels has enough "stuffs and things" to handle it.

 

[Flamestrike]

Agreed. I just think that WOTC underestimated how many groups are going to have access to at least basic +1 weapons at the 10+ level range, and how it just completely changes the durability of the monster when they do.

There is still scope in the Encounter building rules to factor that in though.

Even as simple as the PCs counting themselves as having 'favorable circumstances' based on their magical gear:

Increase the difficulty of the encounter by one step (from easy to medium, for example) if the characters have a drawback that their enemies don’t. Reduce the difficulty by one step if the characters have a benefit that their enemies don’t.

Building Combat Encounters

Using that rule alone, a 'stock' Mummy Lord turns from a Medium encounter (4 x 13th level PCs with no magic items) to an Easy encounter (4 x 13th level PCs with magic items) which at an eyeball, also feels about right.

My gut tells me that the OP however is using CR as his guide for encounter difficulty overall, which is likely what is causing him problems.

 

[Stalker0]

There is still scope in the Encounter building rules to factor that in though.

Even as simple as the PCs counting themselves as having 'favorable circumstances' based on their magical gear:


Building Combat Encounters

That gets a little trickier when your dealing with x2 or more deadly encounters, or just trying to figure out the appropriate XP.

It works, I just think it takes too much work. Its personal preference of course, but I would rather it have worked where the baseline is "assume magic weapons past X level", and then if you don't have them, bump up the difficulty 1 based on the guidelines. There are a lot of monsters that have resistance to nonmagic weapons, especially in the higher CR range....so having to do that adjustment time and time and time again is tedious.

 

[Flamestrike]

Also using that rule, a 'tooled up' Mummy Lord WITH magic items, is still only a Medium encounter for PCs who also have them (the rules assume the PCs would defeat it with zero casualties, and only minor use of healing resources after wards).

 

[Flamestrike]

That gets a little trickier when your dealing with x2 or more deadly encounters, or just trying to figure out the appropriate XP.

I tend to agree; personally I just use the 'eyeball' method for my encounters.

I look at the level of the PCs and (roughly knowing my encounter budgets pretty well off my head) can then just quickly knock up half a dozen or so encounters (for a standard adventuring day) off my head.

A 10th level party (for example) would need a roughly CR15 Solo (legendary for solos is always best) and a mix of encounters of 2-3 x CR 6-8's, 4-6 CR 3-5's an encounter of a CR 10 or so critter with several low CR mook types etc.

Thats for a single adventuring day.

I tend to find after doing such an adventuring day, the math tends to come pretty close to the adventuring day budget (slightly over most of the time, but due to the presence of magic items in my groups, I dont worry about that in most cases).

If Im designing a rarer solo encounter adventuring day, I can really dial it up to Deadly+ and chuck in a solo CR 20 for them to deal with, or 4 x CR 8-10's for the same party.

It's as much of an art as it is an exercise in maths.

 

[Quartz]

Rather than spending so much effort trying to nerf the players, why not let them be awesome and just give the mummy lots of extra HP?

 

[Quickleaf]

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?

FIRE
Environmentally, you could have natron salts or sand or even baking soda pouring into the room (possibly as a Lair Action) which douse any ongoing fires, including things like flaming sphere or wall of fire. This is an environmental solution that suggests certain things about the scene.

There might be a curse that's activated upon entering the chamber or upon dealing fire damage: If you deal fire damage to Mummy Lord, the Mummy Rot curse accelerates, such that anyone afflicted by it suffers the effects faster each round (i.e. 24 hours > 24 minutes > 24 rounds > 2.4 seconds or every round > every turn). This is a "yes, but" solution, "yes you can use fire, but there is a consequence each time you do."

Also remember that against a party packing lots of fire magic, the mummy lord should make frequent use of its third lair action forcing a CON save from anyone casting a spell of 4th level or lower, or the spell gets canceled and they take some damage. You could take that a step further and add "...unless they bearer has the holy symbol of so-and-so, spellcasters casting spells dealing fire or radiant damage suffer disadvantage on this CON save." This is solution tying the story of your mummy & dungeon in, and making it relevant to the players who are invested and paying attention.

MINIONS
For minions – or as inspiration for your Mummy Lord – in my Khemti home game I have a certain variety of mummy known as the “favored of <god name>” which have maximum hit points (90), the Spell Reflection trait (narratively these are protective runes written on their funerary wrappings), and usually some kind of magical item. These “favored” mummies typically have CR 4 (1,100 XP). Alternately, you could just adopt the Spell Reflection runes on the wrappings for your mummy lord.

I just used a necrophidius (bone snake construct with hypnotizing powers) in a recent game, that I converted from AD&D. You might find a use for it...

Necrophidius
Large construct, neutral
Armor Class 13
Hit Points 44 (8d10)
Speed 40 ft.
STR DEX CON INT WIS CHA
12 (+1) 16 (+3) 11 (+0) 7 (-2) 12 (+1) 5 (-3)
Skills Perception +5, Stealth +7
Damage Immunities necrotic, poison; piercing and slashing from nonmagical attacks that aren’t adamantine
Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned
Senses darkvision 60 ft., passive Perception 15
Languages understands the languages of its creator but can't speak
Challenge 3 (700 XP)

Magic Resistance. The necrophidius has advantage on saving throws against spells and other magical effects.

Magic Weapons. The necrophidius’ weapon attacks are magical.

Singular Purpose. The necrophidius is given a single purpose by its creator, such as guarding a treasure or assassinating a target. When its task is done or cannot be completed, the magical animating the necrophidius ends and it crumbles to dust.

ACTIONS

Paralyzing Bite. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 10 (2d6+3) piercing damage and the target must succeed a DC 11 Wisdom save or be magically paralyzed for 1 minute. At the end of each of the target’s turns, it may repeat the save to end the paralysis early.

Dance of Death. The necrophidius rises up on its tail and sways back and forth. Each creature within 30 feet that can see the necrophidius must succeed a DC 11 Wisdom save or be incapacitated, its speed drops to 0, and it cannot look away from the necrophidius. The creature remains transfixed until the dance stops or the necrophidius is killed. A creature that takes damage while under the influence of this power may make another saving throw to break free.

Concept is the Mummy Lord was a Queen/Cleric of Light, who was willingly changed into a Mummy Lord after death to protect their sacred legendary weapon from their Shadow enemy for eternity. The transformation destroyed much of the Cleric's mind, and no longer remembers her life--seeing anyone who enters an enemy and can't be reasoned with. So I didn't want to add too many pure evil creatures for story reasons.

The way you describe her, I'm wondering if the players' intent/objective will be to stomp the mummy lord to the curb... or try to redeem her. Because if it's the latter (or it becomes the latter during the course of the combat), then you don't need a super challenging battle, and instead what you need are some countermeasures / ways they can restore the mummy lord's mind, so it becomes a question of "how do we not kill her, but stay alive long enough to save her?"

 

[Henadic Theologian]

Mummy Lords are basically undead clerics, so have it cast Summon Celestial Spirit as a body guard.

Also you could use the Mummy Lord as a base to build a Mythic Mummy Lord in the style of MOoT's mythic creatures.