Magic item drop

Crossing two of them

What it does

The egg is the interesting one

A self-seeding horse drops a spawn egg carrying its own genotype and its own epigenome, so what comes back out is a clone rather than a horse with the same alleles: the same coat, the same particle colours, the same percentages written on every allele copy.

It is the only thing in the mod that undoes a death, which is why it takes two copies of a recessive that no amount of looking at a horse will reveal.

The sword is a gamble

One enchantment, rolled at the moment of death rather than fixed by the gene, drawn from whatever the world’s registry holds that a sword will accept — so a data pack’s enchantments are in the pool for free. Two horses of identical genotype do not leave identical swords, which makes this the one drop on the locus that is a lottery rather than a certainty.

What you can catch

A fraction of a percent of wild horses are the doubled form of each variant. These are prizes rather than hazards, so the founder table sits on the expressing combinations: a diamond horse can genuinely be caught, and the carriers turn up a generation later.

Health

None whatever. Nothing on this locus affects the living horse.

Its gene carrot

Gene key

horsegenetics.magic_item_drop

Alleles

Dia diamond-bearing, Egg self-seeding, Swd sword-bearing, n

Priority

133 — the magical utility band, beside milk

Reaches the game as

an item_drop effect

Coat effect

none, ever

Replace, except meat

Every value on the item_drop verb replaces the vanilla drop except meat, which is added beside it. The asymmetry belongs to the genes rather than to the verb: a horse that leaves diamonds instead of its leather is a different animal, and a meaty one is the same animal with more on it. It is why the two are separate loci, and why a diamond horse can also be a meat horse.

added.add(stack);
replace |= !"meat".equals(drop.drop());
// ...
if (replace) {
    event.getDrops().clear();
}

The egg is the editor’s egg

It reuses PresetHorseSpawnEggItem rather than introducing an item of its own. The two are the same thing arrived at from different directions — “this exact horse, in an item” — and one of them already has a model, a tooltip and a spawner behind it. The record it carries is StoredGenome, the same payload the stallion seed jar holds.

Horse meat is beef

Not a vanilla item, and the closest honest stand-in needs no new item, no model and no recipe. If the mod ever grows its own, one line in GeneDeathHandler.itemFor is what moves.

A locus that is entirely invisible, on purpose

Nothing about a diamond horse can be seen, felt, ridden or measured. That is unusual even here — most of the hidden loci at least change a number somebody could notice — and it is what makes this one a genuine breeding project rather than a shopping trip.

It also means the locus leans hard on the rest of the mod: the only way to find out what a horse carries is the gene database and the research papers, so this is one of the genes those systems exist for.

Why the three cannot combine

Dia/Egg gives the vanilla drop, not both. A horse leaves behind one thing; two contradictory answers to “what is on the ground” is not a richer outcome, it is an unwritten rule about which one wins. The silent compound heterozygote states the rule instead, and has the pleasant consequence that crossing two prize lines gives an ordinary-looking foal carrying both.