Bereave spell

[GM PDK]

I'm trying to figure out the applications of the bereave spell, shown below for ease of reference. Is meant for offense or defense? it turns the 'laws of gaming physics' on their head, so to speak, and I'm trying to understand it a little better. Does anyone has anecdotes or examples on how you could use it in battle?

Bereave
Source Inner Sea Temples pg. 13
School enchantment (compulsion) [mind-affecting]; Level bard 3, cleric 4, mesmerist 3, oracle 4, psychic 4, skald 3, warpriest 4, witch 4
Casting
Casting Time 1 standard action
Components V, S, M/DF (a broken chain link)
Effect
Range medium (100 ft. + 10 ft./level)
Targets all creatures in a 15-ft.-radius burst
Duration 1 round/level
Saving Throw Will negates; Spell Resistance yes
Description
An overwhelming feeling of loss overcomes the targets, and their allies’ words sound bleak and hollow. Regardless of actual allegiances, affected creatures no longer count as allies for other creatures and always count as enemies for the purposes of abilities, effects, and spells that differentiate between allies and enemies, such as flanking or spells such as bane or bless. Allies of an affected creature must succeed at a melee touch attack to affect the subject with touch spells, and an affected creature cannot voluntarily fail a saving throw even if the effect is harmless (such as cure light wounds). An affected creature still counts as her own ally and can target herself with abilities, effects, and spells normally.

[Kimera757]

You could use it on a rogue to prevent sneak attacks, or on a caster to make it harder to buff their allies. I think the latter example is more useful, but spellcasters tend to have decent Will saves.

I don't think it would mess up the targeting of a Chain Lightning spell, sadly (since you target who you want to hit).

[Derklord]

It would be funny against a group of archons...

[MrCharisma]

So spells like FIREBALL wouldn't be affected (it hits everyone regardless of allegiances).

Spells like HASTE wouldn't be affected either (you can haste your enemies if you want to).

Spells like PRAYER would count you as an enemy (or count your allies as enemies if you cast it).

Interestingly there are some times you could make use of it, like the GOBLIN FOOLHARDINESS trait. I feel like there are better traits out therr for this kind of thing, but it's still a bit niche. If you want it it's there though.