
Deriven Firelion |

Prerequisites an instinct that allows you to change your additional damage from Rage to a different damage type
Trigger You Rage.
You emit a powerful surge of instinctual energy when you unleash your potential. Each adjacent creature takes damage equal to your level (basic Fortitude save against your class DC) of the same type as your additional damage during that Rage.
So how does this work? You rage, activate Scouring Rage as a free action, then anytime someone is adjacent to you during that rage they make a basic Fort save or take damage?

HammerJack |

No, as far as I can tell it's a one-shot burst.
" as your additional damage during that Rage." means "What type of additional damage you added for this rage", not for the duration.
That is also exactly how I read it. The "during that Rage" clause gets rid of the ambiguity that a Spirit barbarian would have with some possible phrasing like "the bonus damage type provided by your instinct."

Reziburno25 |
So from what it looks it's mainly usable for dragonic or spirit barbarian. Where you the barbarian are surronded by enemies or charged them so when you enter rage they roll fortitude basic save. Best example is your spirit barbarian charges into horde of undead and rages causes them to all be hit with weakness.