I was trying to compile a list of all the hidden brutalities (stage, xray, etc.), but I could't find any real single source with all information... so I decided to post here and see if someone knows some that is not already listed...
Here are the ones that i know:
Stage Brutalities
1--Dead Woods: Log impale - Throw Log (interactable near the right corner) at mid/full screen distance from opponent as the final hit of the match.
Conditions - use at least 3 interactables during the match
2--Kuatan Jungle: Head Smash - Use the aztec statue interactable near the center of the stage as the final hit of the match.
Conditions - use at least 3 interactables during the match
3--The Kove: Pirate Pool - Give an uppercut (down + triangle) as the final hit of the match.
Conditions: Hold both front and back kicks (cross + circle) before (and while) executing the uppercut finisher.
4--The Kove: Dead Kills - Throw a corpse at the opponent as the final hit of the match.
Conditions: Hold "Forward" at the directional pad/stick before/while the corpse hits the opponent.
5--Quan Chi Fortress: Hammer Time - Use the hammer interactable (near the right corner) as the last hit of the match.
Conditions: None (that I know of)
6--Lin Kuei Temple: Cleansing Fire - Throw any of the interactable "fires" at mid/full screen distance from opponent as the final hit of the match.
Conditions: Hold "Forward" at the directional pad/stick before/while the object hits the opponent.
7--Outworld Marketplace: Blanche's Revenge - Throw Blanche (the old lady) at the opponent as the final hit of the match.
Conditions - use at least 3 interactables during the match.
***Alternative Stage Brutality Ender - Throw Blanche and hold "Down" at the directional pad/stick before/while the lady hits the opponent.
Dunno if the conditions are 100% right, but these are the ones that I use and the brutalities work...
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These are the secret/not listed X-Ray Brutalities that I pulled (They are all "real" but the only that I know for sure the requirements for now is the Erron Black one, all the others come out "randomly" and the conditions are probably wrong or missing something)
Xray Brutalities
Erron Black- End the match with an X-ray as last hit
Conditions: -use 3 "Sand Trap" Command Grab during the match.
Sonya Blade- End the match with an X-ray as last hit
Conditions: (NOT CONFIRMED) - above 50% health and must hold "Down" during the Xray execution.
Jacquie Briggs- End the match with an X-ray as last hit
Conditions: (NOT CONFIRMED) - execute Xray and hold "Down" during its execution.
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Unlisted Brutalities
Cassie Cage - The American Way.
Conditions: -Must be in Spec Ops Variation, -Must connect The American Way move during the match, -Must end the match connecting "the American Way"
please complete with any move or condition/requirement that I missed...