Emrakul

If Emrakul fails a saving throw, it can choose to succeed instead.

Emrakul has advantage on saving throws against spells and other magical effects.

Any time Emrakul is targeted by a Magic Missile spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, Emrakul is unaffected. On a 6, Emrakul is unaffected, and the effect is reflected back at the caster as though it originated from Emrakul, turning the caster into the target.

Emrakul deals double damage to objects and structures.

Emrakul can use its Frightful Presence. It then makes five attacks: one with its bite, two with its claws, one with its horns, and one with its tail. It can use its Swallow instead of its bite.

Melee Weapon Attack +19 to hit, reach 10 ft., one target. 36 (4d12 + 10) Piercing damage. If the target is a creature, it is Grappled (escape DC 20). Until this grapple ends, the target is Restrained, and Emrakul can't bite another target.

Melee Weapon Attack +19 to hit, reach 15 ft., one target. 28 (4d8 + 10) Slashing damage.

Melee Weapon Attack +19 to hit, reach 10 ft., one target. 32 (4d10 + 10) Piercing damage.

Melee Weapon Attack +19 to hit, reach 20 ft., one target. 24 (4d6 + 10) Bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be knocked Prone.

Each creature of Emrakul's choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become Frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if Emrakul is within line of sight, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Emrakul's Frightful Presence for the next 24 hours.

Emrakul makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite's damage, the target is swallowed, and the grapple ends. While swallowed, the creature is Blinded and Restrained, it has Cover against attacks and other effects outside Emrakul, and it takes 56 (16d6) Acid damage at the start of each of Emrakul's turns.
If Emrakul takes 60 damage or more on a single turn from a creature inside it, Emrakul must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall Prone in a space within 10 feet of Emrakul. If Emrakul dies, a swallowed creature is no longer Restrained by it and can escape from the corpse by using 30 feet of movement, exiting Prone.

Emrakul makes one claw attack or tail attack.

Emrakul moves up to half its speed.

Emrakul makes one bite attack or uses its Swallow.