Polyhybrid is the term for a plant descended from several different hybrids stacked on top of each other, which describes most modern regular releases with four or five strain names in the lineage. The upside is novelty and vigour, the downside is that almost nothing is fixed and every seed is its own gamble. A plain explanation of the term alongside IBL and landrace is provided at https://breederregularseeds.com so the marketing language makes sense. Expect a polyhybrid pack to give you variety, not a dependable plant.