Determining drop sources/rates in Mayhem 4

Hi everyone, since the latest patch added dedicated drops to various enemies and new items in Mayhem 4, I decided to grind out a bunch of farming runs for as many bosses/unique enemies I can stand, and keep track of the legendaries that drop. Hopefully, over time this will help us determine the dedicated drops for each enemy and a rough estimate of their drop rates.

Here’s what I’ve done so far. All on Mayhem 4, NVHM, online:

Mouthpiece
Known dedicated drops (only Mind-Killer so far) are highlighted in orange; annointed drops are marked with (A)
Currently at 50 runs. tl;dr of data so far:

  • 83 Legendary drops
  • Mind-Killer, Mouthpiece’s dedicated drop since launch, appeared 12% of the time
  • Several legendaries dropped twice (roughly 2% appearance rate): Thunderball Fists, Rowan’s Call, Lyuda, Victory Rush, Ten-Gallon, Red Fang, Re-Charger, Transfusion Tracker, Cosmic Stalker, Bitch, Epicenter, Rough Rider, Launch Pad
  • Excluding Mind-Killer, no legendary dropped more than twice

Demoskaggon
Only 11 attempts, I might leave this on the backburner because the chance to get them to spawn at all is low and they’re a boring, spongey fight on M4.

What I need the most help on is knowing what items are new to this patch! I’d like to tag “new/M4 only items” in the spreadsheets but determining what is actually new, and what is just “new to me” is harder than i thought.

I have a post with every legendary and their drop source Loot location spread sheet! New legendaries! Every dedicated drop in the game!