Sorcery/Divine Favor: Karmic Justice

Miracle of the black-haired witch Velka. Temporary autocounter vs. heavy damage. For each sin there is a punishment, and it is the task of Goddess Velka to define the sin, and mete out the punishment.

Finishing up the year with one of the other most mechanically complicated spells of Dark Souls, Karmic Justice. This spell builds up a powerful explosion passively as one accrues damage, and releases suddenly and violently, doing major damage to one's aggressors. Let's put it together below.

Figuring Out The Pieces

First thing, it is a buff that lasts for 1 minute, which means it follows the typical Affliction with a Fixed Duration of 1 minute pattern, so that is pretty straightforward.

The attack itself.

This power works well with this system...

Second, the attack is an Area Effect with an emanation limitation (We don't throw it, the area is centered around us) The attack needs to take less time because it requires 0 turns from us (The time investment is taken into account when adding the buff)

The tricky thing is that the spell's trigger doesn't have a real 100% correlation with a limitation from GURPS. Triggers expect 1 special condition to be true. This spell requires a series of conditions to hold true, namely 5 injuries received in short order of each other. Five is a lot for GURPS, so for the sake of this ability, let's knock this down to 3.

After discussing this in some comments, it seems like receiving three different injuries in a short amount of time is either an occasional or rare trigger depending on the amount of combat that is likely in a campaign. I generally play combat heavy Dungeon Fantasy, so with that as my frame of reference, I decide on occasional

(I need a LaTeX or function plugin for Blogger, that doesn't look nice enough). So, taking that all together, let's stat out the attack component of the ability:
Karmic Justice: Divine Retribution (-5%): Crushing Innate Attack 3 (Mana Sensitive -10%; Area Effect, 2 Yards +50%; Emanation -20%; Reduced Time, Instantaneous, +20%; Trigger, 3 Injuries all within 2 seconds of one or another, Occasional, Dangerous -45%) [15]
The attack is 14.25 points, or rounded up, it's 15 points.
The Affliction to cast it then is
Karmic Justice: Endow (+118%): Affliction 1 (Sorcery, -15%; Based on different Attribute, Will, +20%; Advantage, Karmic Justice: Divine Retribution, +143%; Melee, C Range, -30%; Fixed Duration, 1 Minute, +0%) [22]
This allows one to turn on the Karmic Justice buff for 1 minute with a touch. If the person buffed is attacked 3 times in short order, they will unleash a 2 yard radius 3d crushing explosion on everyone, friend or foe alike.

Other Notes

... But almost makes more sense in this one.

In the original game, you can't use Karmic Justice on a friend, so for a version you can only use on yourself, take the attack, change the cost modifier to -10%, change mana sensitive to sorcery. The ability now costs 13.5 points, or 14 rounded up, and can only be used on yourself. The attack can hurt friends and foes alike, so for a version that doesn't hurt friends, add selectivity +20%, which will add 3 points to the cost of the single-user version, and 5 to the multi-user version. In the original game, this is technically a "miracle" or in GURPS terms, an ability with a divine modifier, but divine and mana sensitive have the same modifier, so it should cost almost the same amount. If you want to use it as a Divine Favor Prayer, it requires Divine Favor 4, or a neutral reaction.