SWTOR changes to Carnage and Combat with Game Update 5.6.

• Ferocity is now stack-based with 2 stacks lasting up to 10 seconds; affecting Devastating Blast, Gore, Vicious Throw, Massacre, Ravage, Smash, and Sweeping Slash; and consuming a stack each time one of those abilities is used
• Ferocity grants an additional 3rd stack if used while Berserk is active
• The triggered effect for Slaughter now lasts up to 18 seconds, up from 15

Sentinel
Combat

• Precision is now stack-based with 2 stacks lasting up to 10 seconds; affecting Clashing Blast, Lance, Dispatch, Blade Rush, Blade Barrage, Force Sweep, and Cyclone Slash; and consuming a stack each time one of those abilities is used
• Precision grants an additional 3rd stack if used while Zen is active
• The triggered effect for Hand of Justice now lasts up to 18 seconds, up from 15

DevNotes: After taking a deeper look at the Carnage / Combat discipline, based on player feedback, we made some improvements to our original changes.