Kain Darkwind's Savage Tide
The powers of Good and Evil sweep up countless other concepts beneath their respective banners, claiming planar territories across the whole of Otherworld. With polar powers so utterly incompatible, there could be only war.
Good vs. Evil. The battle between the celestials of the heavens and the fiends of the hells. It seems so unambiguous at first glance… but if pick off the skin, beneath things aren’t so clean cut. There are noble devil warriors, dauntless and brave; cynical azata just trying to survive; suave propagandists, deal-makers, and spies; and dispassionate chess-masters on both sides who no longer feel anything for the mortals they’re vying over, being all about the Game.
They call it Psychomachia. Both the prize and the battlefield is the mortal soul.
The fight for souls is a constant tug-of-war. Each side struggles to instill its values in the mortal heart. Bitter rivals, unalterably opposed, the sides rarely make common cause against other foes. Even those who may have a grudging respect for their enemies never forget that peace or accommodation is impossible—eventually, one side must destroy the other.
Mostly, it’s a cold war. Agents battle in the shadows, but the aim has long been to get mortals to side with Good or Evil of their own free will. Both sides have learned the hard way that the Mortal Coil can’t survive major open conflict and that it is the choice, not slavery, of mortals that’s needed. If enough souls can be gathered by one side, then eventually, the balance will tip and all the planes will align beside either Good or Evil. Then Good or Evil will be all there is.
Direct intervention on the Mortal Coil is forbidden, an agreement upheld (mostly) by all factions. Of course, rules are stretched, bent, manipulated, and sometimes outright broken by both sides, but archangels, devil lords, and demon princes all largely enforce the rule. Instead, standard operating procedure is inspiration and temptation, sabotage and propaganda, unpalatable political deals for the sake of expediency and battles between proxy forces. Move and countermove, all designed to provide the steady accumulation of souls.
And of course, when necessary, out in the planes there are hot wars where celestials with flaming swords clash against the forces of Hell. With battles of a size and ferocity incomprehensible to mortals that last for centuries with no quarter asked or given. Battles with no negotiation and no hope of resolution because neither side can afford to give the slightest ground. A bloody grind of outsider bodies and expended souls. Many people think the war will never end. Some, especially those not allied to either side and even some jaded fighters, think of it as an eternal game, but to most, it’s an all-out, life-or-death struggle and, in some apocalyptic future, winnable. Every victory changes the battlefield a little, and makes the collection of fresh souls to the cause even more vital.