Face Puncher ( FP in most of my description) with Fire Stone White Elephant/ cryo white elephant hypothetically, most of this build is based on fire stone prefix but finding a way to go cryo would help a lot in terms of frozen enemy damage from melee and such this build also takes advantage of splash modifiers within mozes skill set and on classmod/ artifact bonuses.
take advantage of face puncher to place sticky bombs on all the things.
so youll specifically avoid red tree because the modifiers do not help the guns damage properly, and does not help the damage output on moze.
the reason: the white elephant explosions stem from the melee damage portion of the gun while mozes buffs mostly lean towards the gun damage.which is the base modifier listed on the item card (usually around 200x7 or x14 if youre lucky)
hypothetically speaking since i havent tried it yet, you could attempt to get an ice breaker white elephant if its possible. and getting anointment specific buffs to help the cryo work better. maybe a 2 mag 50% cryo damage bonus but im currently running it with a fire stone. maybe if a cryo stone prefix can exist on the artifact, aim for that because frozen enemies will take 300% bonus damage per bullet from the face puncher. if you go the icebreaker route instead thats 335%.
when it comes to class/artifact bonuses please note: shotgun dmg is a form of "gun damage" and the facepuncher does not scale from gun damage. you want to go for weapon damage because weapon damage just means damage from the weapon. they are two different categories. youll also look out for melee/splash/aoe/ or the element of the artifact you have (if youre doing a cryo build go for efficiency not damage since you need more help freezing) but fire damage works if you dont do cyro.
avoid the bloodletter mod because the abilities it boosts don't help the gun at all. i suggest a blast master. preferably with 4 in vampyr and one in redistribution because you can put another point in redistribution for 10% ammo regen. redistribution with the FP doesn't work on its own since FP doesn't crit, but the elephant bombs absolutely do so thats 10% from them hitting on top of everything else in the tree.
the items themselves work without anointment but in order to make this rly rly shine youll want anointments that benefit your build.
setup: replace fire with cryo in any spot if you want to try the cryo version
Face puncher with 50% bonus incendiary damage for 2 mags or 5% damage increase when you kill an enemy(comes with reload but dont need it)
shield with fire bonus damage for 10 seconds
grabbing a hex grenade with "weapon, grenade, and action skill damage increased by 25% for 6 seconds" would be legit god tier for moze, but if you dont want to aim for something like that i suggest a good old rain firestorm because it will benefit heavily from the class mod.
one thing to note is that if you do go cryo, to use the turrets with cryo instead but otherwise youll want explosive rounds for the splash advantage.