A named threat of Aventhine Sewers, encountered rarely and never in numbers - real Dungeons & Dragons statistics, no auto-computed shortcuts.
Layered on top of the module's own combat AI, which still picks targets and positioning. The fight below moves through real hit-point-gated phases; every save DC and attack bonus computes from the stat block above at runtime.
He doesn't answer in place - a stack banks on the caster themself and he clears every other action to close the distance at once.
Whoever he's Studied hardest becomes the round's target, tracked the same way he tracks a caster's own tell.
A melee blow that strips magic outright, then a permanent haste that never leaves him.
CR 8 is set against Aventhine Sewers's own real ambient ceiling, not auto-computed from level alone - a genuine Ranger 5 / ShadowbaneStalker 3 build at 8 total levels.
Hit points (48) follow this project's own average-hit-dice convention, and every save/attack bonus derives from the ability scores above at runtime - nothing here is hardcoded past the phase gates themselves.
Boss-flagged (bypasses the drop-rate roll, two loot-generation passes) and gated to a single spawn - only one The Unweaver is ever up in Aventhine Sewers at a time.