A warband chief who worked out that his own people are worth more to him dead than alive. He does not protect his goblins and he does not fight beside them. He eats them, and cuts a notch for each one.
That goblin dies on the spot. Ogruk keeps a permanent +1 to hit and a slab of temporary hit points for it, and gets visibly larger. Every prior escalating boss here feeds on the PARTY — damage taken, spells cast, saves failed. This one feeds on his warband.
He spends the whole round bellowing another coast goblin into the fight — a bruiser once he has three notches. That call is the party's window, and the resource race is entirely in their hands: every add left standing is a notch he is going to take.
The tally is spent at once: a warband roar for 3d8+8 sonic in 10m, Will against being frightened, Fortitude against being put down, and a fifth of his own hit points back. The notches themselves stay; only the tally resets.
CR10, one notch above Goblin Coast's prior Barknuckle ceiling and matched to Nabb and Ysmene, with Malbrek at CR11 as the batch's apex.
He is the bestiary's first Warchief and, deliberately, nothing like the coast's existing three: Grisla is a divine caster, Tideglass a druid, Barknuckle a giant-blooded fighter. None of them interact with the trash population at all. Ogruk turns the ordinary coast goblins — the ones already in the spawn table, no new blueprint required — into the fight's actual resource, in both directions.
The call is capped at eight over the whole fight so he cannot conjure an unbounded warband, and the tally resets on each Reckoning so the roar can fire more than once in a long fight without the permanent bonuses running away.
No spells, no epic spell — a martial prestige class at CR10.