So, having recently acquired a riven mod that decreases finisher damage, i began trying to understand exactly what finisher and finishing damage were, hie they really work and how various mods affect each. This thread contains my findings and remaining questions and hope it will be helpful to you.

Summary - We need to distinguish at least 4 different sources of damage :

We also need to identify exactly what does each of the damage types listed above and what mods and riven mod rolls can affect the damage types listed above. More information about that below...

Resources :

Finishing Damage is a unique damage type that completely ignores armor and shields, damaging health directly without any kind of damage mitigation. Finishing damage does not produce any kind of status effect.

The wiki lists under "finishing sources" "abilities with the finisher damage type" - so you would think this would include finishers if you just read this page. Right? No, wrong... Look at the "Finishers page" next:

Contrary to the common belief, Finisher maneuvers do not inflict Finishing Damage; the damage bypassess armors but not shields. Players performing finishers are immune to any kind of damage for the duration of the animation.

Are you confused yet? There's more...

As long as an enemy is unaware of the Tenno presence, a STEALTH ATTACK may be executed on them. To perform a stealth attack, the player must approach an enemy from behind and activate the stealth attack prompt. Stealth Attack Damage = Weapon Damage × Stealth Multiplier × Weapon Multiplier

Stealth attacks ARE finishers and ARE affected by mods that increase "finisher damage". Mods that increase "finisher damage" include : Covert lethality, Retribution (?), Finishing touch, fatal teleport, savage silence, radiant finish, savagery, ferocity, helminth ferocity do affect stealth attacks. They are also affected by melee rivens that increase "finisher damage"

There is a separate and different 8X melee bonus for standard melee attacks (which are not finishers) dealt to unalerted enemies while the player is in stealth.

STANDARD MELEE ATTACKS are affected by a 8.0x stealth damage multiplier when attacking UNALERTED enemies, or when cloaked by an ability (Smoke Screen, Invisibility or Metronome). This damage multiplier changes the color of regular damage pop-ups from white to yellow (similar to critical hits). As long as you are invisible, the 8.0x stealth damage multiplier will reset every 2 seconds after an interaction with an enemy (Shooting, melee attack, physical contact). Stealth Melee Damage = Weapon Damage × Stealth Multiplier.

Stealth Multiplier is always exactly 8.0. Critical hits while under these effects will still appear yellow and will simply include the stealth damage multiplier in the final result. Stealth Melee Crit Damage = Weapon Damage × (Stealth Multiplier + Crit Multiplier - 1)

STEALTH MELEE DAMAGE IS NOT THE SAME AS "FINISHER" or "FINISHING" damage. Now there is YET ANOTHER category :

"Enemies open to finisher damage also take 4x more melee damage, for reference see Radial Blind. "

contrast with

"For spin 2 win this does not increase slide damage but it does help lead the lamb to the slaugher: "

It appears to be the case that (SOME?) mods that affect finisher damage increase damage done to enmies open to finishers. This is probably why banshee's "savage silence focus farm" is a thing and an alternate to equinox. If savage silence did not increase the damage done to enemies open to finishers there would be no reason to equip it for adaro runs as regular silence also stuns enemies and opens them to finishers. In a "perfectly executed" adaro run, "finishers" are never used (because only slide attacks are used and they aren't finishers)... It is not clear which mods have an affect on damage of standard attacks (ex: slide attacks) done to enemies open to finishers nor if "finisher damage" mods on melee riven mods affect standard damage done to enemies open to finishers. Whether this is true or not could completely make or break a riven mod intended to be used on weapons for adaro farming if that riven had a blessing or curse for finisher damage (finisher damage would be a great curse if it has no effect and a terrible curse if it does).

Edit to clarify the above: The added damage to enemies open to finishers is only because of the stealth modifier. There is not a spearate modifier for enemies open to finishers that is not related to stealth. Savage silence adds damage because it temporarily blinds and stuns enemies making them susceptible to the 8X stealth modifier. The finishing touch mod and rivens that decrease finisher melee damage have no effect on the above because they only affect finisher attacks.

Other resources:

Finishing Moves

  • Stealth "finisher" (Also called Stealth Attacks, easily confused with attacks that benefit from the stealth damage multiplier)

  • Ground "finisher"

  • Counterattack "finisher"

  • Other "finishers" (malicous raptor, etc)

Finisher Damage

  • Ash's Bladestorm

  • Hydroid's Tentacle Swarm

  • Trinity's Energy Vampire

  • Slash Procs

Then we have stuff that affects "Finisher Damage"

  • Savage Silence - Savage Silence says it increases finisher damage you deal for the duration of the ability by 300%. It actually increases the damage of finishing moves, bladestorm, and tentacle swarm done to enemies affected by Silence by you or by allies. Doesn't affect slash procs or Energy Vampire.

  • Radiant Finish - Radiant Finish says it increases finisher damage done to blinded enemies by 300%. It actually increases the damage of finishing moves, bladestorm, and tentacle swarm. But not slash procs or Energy Vampire.

  • Finishing Touch - Finishing Touch says +60% Finisher Damage. It increases the damage of Finishing Moves you do. But not Bladestorm or Tentacle Swarm. I get that those are abilities and this is a mod on a melee weapon though, so this isn't so bad. BUT the mod DOESN'T affect the damage of slash procs applied by the melee weapon.

Is the dmg done by slash procs affected by + or - finisher dmg mods and rivens?

Slash procs are based on the damage that caused them, so yes, more finisher damage when proccing a slash proc, will make them stronger or weaker depending on the riven but I believe only for the prompted finishers.

It increases the damage for ground finishers as well. Even though they don't deal 'Finishing damage' like the other types of finishers. Also counterattack(parry) finishers but nobody uses those ever.

Edit : Here's a video that reinforces the above - the finishing touch mod does not increase the damage of slash procs unless those slash procs were inflicted by a finishing move (example: ground finisher) is shown in the video : https://www.youtube.com/watch?v=Qe2uWm1BQKk. Thanks to dappermuffin in the comments for sharing it.

Concluding thoughts

The terminology is quite confusing and could really use some clarification in the game. The wiki is good but some things are still unclear even after reading all of the articles. If you have done testing on the above especially the damage done to enemies open to finishers by non finisher attacks with rivens that affect finisher damage and mods that affect finisher damage i'd be interested in your results.

Thank you and I hope this helps people.