Pox of Rumors
removes the "scry" from "scry and die" for anyone with intelligent underlings. You can, from your house, curse the big bad (or a king) and make his men drop one step in relations immediately and risk dropping further each day. Note that nothing says this returns to normal when the curse is broken. This isn't even from some companion/campaign setting the editor wasn't paying attention on, it's from a hardcover! If you have a hair you can even tank their willsave to this.
Cherry Blossom Spell adds ability damage to a spell that does damage but gives a fortitude save to negate it if the spell doesn't have a save already
. This means you can apply it to a spell that has a save, still does damage on a save (which includes most AoE blasts and some blasts that deal damage and have a save or rider) and can hit multiple times for repeated ability damage. Looking for a spell to abuse this with, I realized Magic Weapon has a save to negate it, but the save is for the object it's cast on and won't stop its from doing damage. Even if the GM houserules it can't be cast on a magic weapon, you can still apply it to mundane arrows shot by a magic bow. Given a good bow user has fires two extra arrows (from manyshot and rapid shot). When you first get the ability to pull this off that's 4 arrows for 8 (5 for 10 with haste, which you can also cast by that point) unresistable ability damage a turn, and you could theoretically apply it to both the bow and arrows. Average mental ability scores on monsters tends to be sub 20, so you're KOing anyone this is used against very quickly.
edit: Nameless One
feat gives us a way to die in character creation. Take the feat, affirm your identity and eat negative levels greater than your level.
edit: Final (penultimate if counting the module that's a kickstarter/Royal Ascension bonus for the Kingmaker VG) 1E book is out. Soulbound Summoner trades their Summon SLA for extra evolution points and ability to summon their Eidolon the same day it "dies" if they heal it enough. You also get an Oracle curse and this action economy breaker
At 13th level, the eidolon can draw from its summoner’s power to cast spells. The spell must be a spell that the summoner knows, and the summoner must expend two spell slots of the same spell level or higher to allow the eidolon to cast the spell. Expending spell slots in this way does not take an action. The eidolon uses the summoner’s caster level, feats, and casting statistics for all spellcasting purposes. The eidolon must be able to meet all other requirements for casting the spell, such as being able to speak for spells requiring verbal components and providing any material components or focuses for spells that require them. The eidolon must be able to move its body to cast spells with somatic components, but it does not need to have the limbs (arms) evolution.
edit: Gunpowder Ooze is a CR14 monster that can be killed by a pair of thrown lamps. When hit by fire damage it does AoE fire damage and splits. Hit it with fire damage once and you've got two of them. Hit it with fire damage again and it explodes, dealing fire damage to its spawn which causes it to explode and split in turn in a loop that only ends when the oozes have killed each other. Could very well be intentional given it's an ooze, and oozes are typically intended as part of traps. As a trap they can do serious damage to anyone not immune to fire. Assuming artificial stone walls, it only needs 5 iterations at average damage to destroy a segment of the dungeon.
edit: Secret of Magical Discipline from Chronicle of Legend lets you expend a slot to cast ANY spell of that level once per day (take it multiple times for multiple uses) as a full round action. No class list restrictions. Requires a level in Loremaster, but that's not a bad prestige class at all (full casting, easy qualification, no heavy fluff).