Help me make the most bitter cocktail

I’ve been cooking up the most bitter cocktail ever. Including some of the most divisive ingredients. I need suggestions for additional ingredients.

So far ingredients include:

Fernet Branca
Jepson’s Malört
Campari
Aperol
Jäegermeister
Angostura Bitters
Peychaud’s Bitters
Absynth
Coffee liqueur
Tonic water
Moxie
Espresso

Note: not looking for weird conflicting flavors, so no orange juice or vermouth or olive brine.

I’m talking bitter.