Reference (SimulationCraft and Icy Veins)

Reference only, off by default: the optimized Beast Mastery priority. Charges, cooldowns and procs are hidden from addons in Midnight combat, so it cannot run there; read it, or clone it to experiment. Focus is hidden on Retail. Calls your pet, marks the target before the pull. Barbed Shot just before Bestial Wrath or before it caps; Bestial Wrath; Kill Command on Howl of the Pack Leader or Nature's Ally, or freely while Bestial Wrath is far off; Cobra Shot on Cobra Fang; Cobra Shot; Barbed Shot when Cobra Shot is unaffordable. Dark Ranger: Black Arrow during Withering Fire and Wailing Arrow as it ends. Three or more enemies (two with Beast Cleave): Wild Thrash to start Beast Cleave, then Kill Command, Barbed Shot and Cobra Shot while it lasts. Reminders: Bloodshed and the Assisted premade's utility reminders.

Adapted from SimulationCraft default action list: Beast Mastery, Icy Veins: Beast Mastery Hunter rotation (12.1.5).

In game: /rm set beastmastery-guide chooses it by hand; it loads only for its edition and class, and is listed only for the specializations it is for. It ships disabled: an alternative to the recommended rotation for its specialization. Turn it on in game (Rotations, then Enabled) and either turn the other off or give this one a higher priority.