The Tias: Soulbound Gems As Magical Keepsakes

tldr; there are dozens of magical gemstones, each with a soul-bound princess trapped inside of them. Each conveys a small bonus, while collecting several conveys a cumulative set bonus.

The Ishnindah is not one of history's actors. She lurks in the background, plying her trade with the stoic fools of each era. Her footprints stretch across millennia, backwards and forwards.

Though she has lately preferred body parts as payment, there was a time when she preferred maidens of royal extraction. Want a spell that causes an enemy to only gain nutrition from cannibalism? Turn over a princess. The Internal Struggles of three centuries ago were largely an arms race of purchasing death-hexes from the Ishnindah. The royal families of the great cities mined their extended family trees for suitable candidates, turning them over by the dozen. Much magical lore was accrued from these transactions (the Ishnindah's well of magic does not run dry), though it was largely destroyed later, when the faith of the Idolatrous Lords waxed supreme.

The Witching Ways
The Ishnindah confounds analysis. But we know very well what happened to the princesses given over to her: their soul were trapped in gemstones, used to power their magics. There are at least fifty of them, each made by the Ishnindah and traded away. Over the centuries they have fallen into the hands of many adventurers and monster troves. In my game there is a flat 5% chance per incidence of treasure that a tia is among them.

The gemstones are called "tias". Keeping them in your possession only counts as one magical item, total. I use a trinket slot. If you use the absurdly granular Pathfinder 17+ item slot system, please stop. If you persist, maybe use the amulet slot.

The Tia Stones

Each tia stone conveys a small magical bonus, while the total number of tias equipped by a character conveys a cumulative "set bonus".

Set Bonuses (total mumber of tias: bonus)

• 3: You have resistance (half damage) against acid and poison.
• 5: You have +1 to all of your saving throws.
• 10: Your spells inflict +1 damage.
• 20: +2 to all saving throws.
• 35: Your spells inflict +2 damage. 
• 50: You cease aging, gain +3 to all saving throws, and can infallibly detect lies and detect magic as per those spells.

Individual Stones

I really dug deep for these t-named gemstones. You should come up with your own, too.

• Tia Topaz: You heal 1d6 hit points from healing spells of 1st-level or higher.
• Tia Tigerseye: You have a +4 bonus to Sense Motive checks.
• Tia Turitella: You are immune to slow and similar effects.
• Tia Tanzanite: You have resistance (half damage) against electricity.
• Tia Tourmaline: You can cast cure light wounds twice per day.
• Tia Titanite: You can cast a weak version of dimension door, once per day. It functions as the normal spell, but with a range of only 100 feet.
• Tia Tektite: You ignore the first incidence of ability score damage, each day. If that doesn't match your rules set, it instead makes the player immune to the first debuff to affect them, each day.
• Tia Tortoiseshell: You have +1 AC.
• Tia Turquoise: Outsiders and spirits have disadvantage when attacking you.
• Tia Tsavorite: You have resistance (half damage) against attacks of opportunity.
• Tia Thomsonite: You have +3 initiative.
• Tia Tugtupite: You are immune to bleeding effects. You have +5 max hp.
• Tia Taaffeite: You can cast meld into stone once per day.
• Tia Tinaksite: You are immune to damage and suffocation from non-magical heat and fire. For the purposes of this tia, magma and other geothermic heat is magical.
• Tia Tyuyamunite: You shed a ghostly green light within a short radius. You are immune to blindness, magical or otherwise. If, for example, your eyes were gouged out, you could still see so long as you had this tia.
• Tia Tsumebite: You can see through barriers of 1 inch thickness or less, including fog and many doors. You can't see through lead or other unusually dense materials, though.
• Tia Tsumcorite: You are immune to color spray, prismatic spray, and any other "color-based" spell. You have +2 speed.
• Tia Trona: Your fire spells inflict +1d6 damage.
• Tia Triphylite: You cannot be knocked prone.
• Tia Tridymite: You do not suffer any ill effects from excessive atmospheric pressure or the lack thereof. You are immune to decompression sickness. You can also hold your breath for up to a week.
• Tia Tremolite: You have fire resistance (half damage).

The Koros

A Koros bird-lancer.

The Koros are a race of barbarous, nomadic bird-riders. They reside in great numbers at the grasslands of Arhelia, where they and their vast herds of bird-horses live, fight, and reproduce. The lands of the Koros are vast and their internal struggles significant, but when a powerful leader emerges the Koros are willing to gather in great hordes and ride against the degenerate cities-states of their region of the world.

The Koros are polygamists. Koros men are expected to have at least three wives, each of whom will birth as many children as possible. There is also a well-established tradition allowing for women that are successful warriors to be treated similarly to men, including retaining numerous wives.

Portrait Of A Bird-Lancer

A Koros warrior typically owns two well-trained bird-horses, a steel-tipped riding spear, a bronze sword for close-quarters fighting, a quiver of filth-smeared javelins, a suit of reinforced leather armor (perhaps incorporating a breastplate if they are wealthy), a pouch of antiseptic salts, decorative bones taken from slain foes or lovers, and feathers from long-dead mounts. Though not an especially inventive people, their bird-horse kit includes stirrups (an innovation other cultures have yet to value).

Successful warriors are rewarded by ritually inscribed tattoos that protect them from various harms. They may include any or all of the following:

• Whorl Against Witchcraft: The Koros has advantage when saving against spells of all kinds. This is the most commonly found tattoo.
• Whorl Against Disaster: The warrior never accidentally drops or breaks their spear. They cannot botch.
• Whorl Against Cowardice: The warrior is immune to fear and being slowed, and their mount has +2 speed.
• Whorl Against Weakness: The Koros inflicts an extra +1d6 damage with a charge attack. They are also immune to most diseases.

Some Koros also procure flasks of blessed water, to be sprinkled over a troop of cavalry and imparting resistance (half damage) against ranged and AOE attacks for an hour or so.

Riding Birds

Every Koros bird-knight can use their mount to leap over 20 feet in a single bound, aiming their lance with the full weight of their mount behind it. Such an attack is devastating, probably inflicting double damage.

The bird-horses are quite dangerous on their own. Their claws can disembowel an armored man. A pecking bird-horse can easily crush a man's skull or rip the flesh off a limb. Skilled riders will incorporate their bird's natural talents into their combat routine.

The Taboos Of The Bird-Tribes

They have many taboos. The most important:

1. Bodies must be brought to the gates of the afterlife. The gate is located in the ruins of an ancient temple in the center of Arhelia. To die and not be sent through the gates is to consign your soul to inflict grief upon your descendants. As I discuss elsewhere, this particular belief eventually results in a great deal of trouble.
2. Digging in the soil is what farmers do. Do you want to be a slave to the land? I didn't think so. Do not ever dig in the soil. For that matter, most work unrelated to bird husbandry is beneath a proper Koros.
3. The word for magic that is not bird-shaman magic is witchcraft. Witches must be killed.

The piece continues...