Gargantuan Monstrosity, unaligned
Armor Class 15 (natural armor)
Hit Points 248 (16d20+80)
Speed fly +120, walk +20
Challenge 11
Saving Throws cha +3, con +9, dex +4, wis +4
Skills perception +4
Senses passive Perception 14
Keen Sight. The roc has advantage on Wisdom (Perception) checks that rely on sight.
Multiattack. The roc makes two attacks: one with its beak and one with its talons.
Beak. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 27 (4d8 + 9) piercing damage.
Talons. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 23 (4d6 + 9) slashing damage, and the target is grappled (escape DC 19). Until this grapple ends, the target is restrained, and the roc can't use its talons on another target.
Source: 5e Core Rules · OGL/Open