Eternal Engine+4

No Pal spawns with Eternal Engine as a guaranteed innate passive. It appears as a random passive when catching wild Pals — but it's a rare roll, so expect to catch many before finding one.

The most reliable path is selective breeding: if either parent has Eternal Engine, the offspring has a chance to inherit it. Stack it across generations by always using a parent that carries it — each child can inherit up to four passives total.