To make each tier 4 purge thrall more unique, I suggest of giving them each a unique ability that nobody can share with others.
For example if you use a tier 4 purge cook, named such as: “Thramok Bark Cooker”, then maybe he could be given the ability to convert/‘cook’ directly tree bark at a stove into gruel or such. Bear in mind this is the unique ability as only available for him, not even other tier 4 purge cooks such as "Shina Waste Collector’, which has the ability to to produce putrid meat as by-product when cooking meats over open fire and so forth.
Or you could have alchemist “Tumma Goldchemist” to produce synthetic yet authentic gold dust over a firebowl cauldron by mixing corrupted stone with silver and steel bars, as different from “Vita Sanguinis” who can produce normal mortal blood by converting demon blood from the cauldron.
Or you cold have a purge tier 4 archer named “Syla Venom Blood” to shoot snake arrows by default as compared to “Ragnas Flesh Searer”, who’ll use firespark arrows instead. Fighterwise maybe “Zorkon Bonecrusher” will frequently use heavy attacks when given a maul, yet “Zarra the Fencer” will use more light attacks when given a single-handed sword, +25% of additional damage.
This will make players more incentive to hunt down ‘purge-only’ unique thralls. (But… errr… might as well enticing players to raid other players’ bases for thralls as well, I guess?
)
Anyway, what say you all?