Multiattack. The bone roc makes one Beak attack and two Talons attacks.
Beak. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit:14 (2d8 + 5) piercing damage.
Talons. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit:12 (2d6 + 5) slashing damage plus 10 (3d6) necrotic damage.
A bone roc is a birdlike Undead that can incorporate the bones of multiple flying creatures. Despite their name, bone rocs aren't always reanimated skeletons of rocs. You may customize a bone roc by rolling on the Bone Roc Sources table to determine the type of bones used and how that affects its stat block.