A Really Fun, Complex Fight

 In D&D, you run into a balancing issue in combat - not difficulty, but excitement. A single scary monster can be a lot of fun, but often as a DM, you run into issues where a single status ailment trivializes the fight. I'm running a campaign that has hit tier 4, so every spell (of the players' classes) is on the table. Even with legendary resistances, there are things that can bypass that, such as Otto's Irresistible Dance or simply grappling them.

So, the answer would seem to be to use a greater number of less powerful monsters. But you can also run into an issue where if you go too low, the monsters don't have the power to meaningfully threaten the party, even en masse.

I like big, chaotic battles with lots of moving parts, but they can be a real slog, with a lot of the DM kind of playing against themselves while the players just sit there.

Tonight, I found a possible solution.

The party is hunting down an evil Ancient Wasteland Dragon who, unbeknownst to them, is being manipulated by a disguised Mind Flayer posing as a Simic Biomancer. The Guildmaster of the Gruul Clans was attacked with a dangerous curse, and his majordomo, a Fire Giant Dreadnought, worries that his honor and standing in the guild has been damaged by allowing this to happen. So, Dazhed, the giant, has offered to accompany the party, and is bringing with him two Ogre lieutenants and "The Wrecking Crew," twelve Gruul Anarchs who are the kind of Mad Max-style madmen who would leap off a speeding vehicle to take down their foe.

The key is: I divided the NPCs amongst the players - each player had control of either three of the twelve anarchs or one of the ogres (using the Flee, Mortals! version that has more fun abilities). They control these in addition to their own characters.

It's honestly pretty manageable, and I only have to run the Fire Giant and the monsters, which in this combat is simply an Elemental Locus (Tome of Beasts) and a Mist Hulk and Cinder Hulk (both from Bigby's).

We only got through one round of combat tonight (starting halfway through our 4-hour session) but I think people really enjoyed it - the Anarchs are simple, but fast, and the Ogres have a really fun "human bowling" ability that is meant to be used on players when the ogre is hostile, but in this case one of the Anarchs voluntarily got thrown, which knocked the Elemental Locus prone (doing a grand total of 1 damage, but prone!)

The fight is chaotic and unhinged and fun, and while it's not, like, quick, it seemed the players were really having a good time.