Entrance
Wyrmbog cave, southern Dustwallow Marsh (near Forever's Alcaz Prison zone).
Loot and attunement
Attunement 'TBD in Forever (Yes in Classic)' (Wowhead). Tier pieces obtainable across all three raid sizes (Zierhut/Nuthals, The Sun interview via Wowhead). Epic raid drop appearances go only to the player the item binds to.
Description
Returning original 40-player raid unlocking alongside the two new raids; Blizzard has not confirmed whether it is reworked.
Forever evidence
confirmed_panel (roadmap slide); Clay Stone listed 'Onyxia's Lair at 40 players' for Dec 9.