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?

 

[DurrandDurr]

That must have pretty much maxxed all the dice.

He poured Divine Smite on top of the Crit.

 

[CleverNickName]

Yeah, I agree...that's going to be a very quick and anticlimactic battle. You should give the mummy lord some backup. Have a few Deathlock bodyguards who can cast Counterspell in the room, or maybe a harem of banshees.

 

[DurrandDurr]

It really depends on how taxed on resources the PCs are when they get to this fight. If they are fresh, then it probably doesn't matter how many additional mummies you add - they'll get dusted fairly easily with characters at that level. You can basically throw out the CR guidelines at this level if your players have any level of play experience.

I would suggest you give the mummy lord counterspell and have Cast Dispel Magic as a legendary action. Then make sure to use the Lair Action that wracks spellcasters with pain. An environmental effect like bad air or even explosive gases can also put a damper on the fire magic. You could even make the chamber air tight which would be neat - just create some kind of option to get some air in the room like busting down stone doors or something.

Set up the terrain such that the mummy can stay out of the reach of the melee PCs for as long as possible and harry them with spells (keep tabs on concentration) and dreadful glares while mummies, swarms of beetles, or whatever else is thematic whittles them down. The legendary action that allows it to turn into a whirlwind might help with mobility. It wouldn't hurt to give it misty step though. I would also get rid of the immunity to dreadful glare on a successful save.

I can't underscore enough that terrain is going to be your friend here, both in presenting a cool thematic encounter, but also creating a tactical challenge to the PCs. So I recommend spending at least as much time thinking and designing that as you do in picking monsters.

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.

 

[CleverNickName]

If it's a "final boss" encounter, you should add plenty of Lair Actions and Legendary Actions, too, to keep things interesting. Keep the party moving around, and try to make it very hard for them to safely stand in the same place doing the same action over and over again.

 

[Quartz]

He poured Divine Smite on top of the Crit.

Ah yes, that will do it.

 

[Quartz]

or maybe a harem of banshees.

Shades of Lord Soth.

 

[DurrandDurr]

Just for the record, the mummy lord is regarded in my game as THE MOST DISAPOINTING MONSTER OF 5e. Its hitpoints are so stupidly, laughably low for a CR 15. I think my 7th level party killed it in a single round, not even doing anything fancy.

Lasting 2 rounds? You have a paladin in the party, he might literally solo it himself if got some crit smites.

In all seriousness, layer on the buffs like butter....the mummy lord needs so much help.

Thanks for confirming my suspicion that the CR rating was WAY off. lol It's no Mumm-Ra.

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

 

[jgsugden]

There are a lot of games, apparently, where DMs need to learn how to make a combat interesting and challenging without resorting to making the monsters overpowering.

 

[DurrandDurr]

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. A Deathlock might work, ht @CleverNickName

So throwing in 3-4 mummies in addition to the Lord won't be a TPK, then?

Thanks for all the great and quick responses! This is my first post here. I appreciate it.

 

[DurrandDurr]

There are a lot of games, apparently, where DMs need to learn how to make a combat interesting and challenging without resorting to making the monsters overpowering.

Agreed. I'm learning that now, and trying to incorporate it. Dungeon Dudes have a great video on Combat (part 2 of 3) that was very helpful in thinking about combat. Waves of 'grunts' and such. But the CR Solo monster chart in XGtE they use as a starting point was unhelpful since the Mummy Lord has such a high (and apparently overrated) CR rating.