Blessing of The Pig (Recharges after a short or long rest). If the pig were to drop to half it's hit points, the pig instead resets to it's full hit points. It then gains a +10 to all damge the pig does and a -10 reduction to all damge it takes.

Fly By. If the pig flys past a creature, it doesn't provoke opportunity attacks.

Magical Attacks. The pig's attacks count as magical for the purpose of overcoming immunity to non magical attacks.

Power Surge (Recharges after a long rest). When you use your legendary action, you may use this feature to use the same action twice.

Regeneration. The pig regains 30 hit points at the start of its turn. If the pig takes psychic damge, this trait ceases to function. The pig can only die if it starts its turn with 0 hit points.

Running Attack. If the pig moves at least 30ft (flying or walking) before hitting a creature with a headbut attack, it deals an extra 13 (2d12) bludgeoning damge.

Multi Attack. The pig makes 3 attacks (which includes the Cloud of Gas action), but one has to be its headbut.

Headbut. Melee Weapon Attack: +15 to hit, reach 10 ft., 1 target. Hit: 41 (4d12 + 15) bludgeoning damage. If the creature is large or smaller, it must succeed on a DC 25 strength saving throw or fall prone.

Powerful Legs. Melee Weapon Attack: +15 to hit, reach 10 ft., 1 target. Hit: 41 (4d12 + 15) bludgeoning damage.

Cloud of Gas. The pig cuts the cheese. All creatures (apart from itself) in a 300ft sphere must make a DC 28 constitution saving throw. A creature failing the save takes 128 (12d12 + 50) necrotic damage and 48 (5d12 + 16) psychic damge. A successful save means it takes half as much damge.

Teleport. The pig magically teleports 60ft to a point it can see.

Fart. The pig makes one Cloud of Gas attack.

The pig has 3 legendary actions that it can take after any other creature's turn. It regains expended legendary actions at the start of its turn.

To Many Beans For Breakfast  (Costs 3 Actions). The pig makes 2 Cloud of Gas attacks. 

Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.