Maximum number of things adding to damage at once

[strangebloke]

So, I thought I'd start a little competition!

On a single attack, what is the greatest number of modifiers you can add to damage?

I'll be looking at a few different categories, but nonetheless I do have some ground rules:

Rules:
1. No magic items. No poisons or alchemist's fire or anything like that. The focus here is on the builds, not the loots.
2. You only get to count your own abilities. No friendly spellcasters or auras.
3. If you can get an extra damage modifier via surprise or some other situational effect, feel free to count it.

Categories
1. no multiclassing
2. multiclassing and spells
3. no spells or multiclassing

I'm also curious just to see the best entry for any given class.

Off-the-cuff builds
1. Scourge Aasimar Fiend Warlock
greatsword + STR + GWM + hex + hurl through hell + eldritch smite + lifedrinker +racial ability + GFB= 9

Bugbear Hunter
greatsword + STR + GWF + GWM + hunter's mark + colossus slayer + zephyr strike + racial ability + GFB= 9

2. This is, inevitably, going to be a very very silly build.

3. Bugbear Zealot (GWM)
greatsword + GWF + STR + GWM + rage + zealot rage bonus + racial ability = 7

[Hesh]

How do you have multiple Concentration Spells? Hex+Wrathful smite?

Oathbreaker/Paladin gets 11 if you mean Divine Smite, and it can add Oathbreaker aura to it too.

[strangebloke]

How do you have multiple Concentration Spells? Hex+Wrathful smite?

Oathbreaker/Paladin gets 11 if you mean Divine Smite, and it can add Oathbreaker aura to it too.

Derp.

But yeah, I expect straight paladin to be a contender alongside warlock and ranger

Lesse...

1. Scourge Aasimar Oathbreaker
greatsword + STR + GWF + GWM + crusader's mantle + IDS + Divine Smite + CHA + racial ability + GFB= 10



I put some more thought into this. Basically what it comes down to is something like this: You get one modifer for each of the following:
Weapon
fighting style (dueling or GWF)
attack modifier
weapon feat
concentration spell
bonus action damage booster (zephyr strike, kensei shot)
blade cantrip

...and then class features. But most only get 1.