Predator
CondDmg
Bonus damage while the enemy is above 75% HP.
Rolls between 5% and 30%, scaling with the gear score of the item carrying it.
Forge mods that grant it
Spending one of these puts the perk on your gear instead of waiting for a roll.
Rolls on
BowSwordWandCrossbowGreatswordStaff
A drop or a craft of these types can roll this perk into one of its slots.