Phoenix was released in the 1990s, related through breeding lineage to Target and Challenger and developed as another entry in the modern English dwarf-hop wave alongside First Gold and Pilgrim, all bred within a fairly compressed period to modernize English hop growing for mechanical harvest without abandoning the aromatic character English brewers expected from their domestic hops.
At 8.5-12% alpha acid, Phoenix sits between Challenger and Target in bittering strength, with a spicy aroma carrying a mild citrus edge that positions it as a genuine middle ground between Target's assertive sage-and-wood character and the gentler, more purely spicy profile of older English varieties. It's a flexible, if not particularly singular, addition to the modern English dual-purpose family — a hop that does its job competently without needing to be the specific, singular reason a whole recipe gets built around it in the first place. Phoenix's middle-of-the-road English alpha splits the difference between its two better-known relatives, which the IBU calculator will confirm on a real bittering charge.
Target and Challenger both serve as reasonable substitutes depending on whether more or less alpha acid is the priority, since Phoenix sits genetically and aromatically between the two. English bitter and pale ale both use Phoenix as a practical dual-purpose hop. Its alpha ceiling nearly matches Target's floor, part of why the two are treated as close enough to swap when only bittering strength, not the sage note, matters to a recipe.