Calydonian Boar

Charge. If the boar moves at least 20 feet straight toward a target and then hits it with a tusk attack on the same turn, the target takes an extra 14 (2d8) slashing damage. If the target is a creature, it must succeed on a DC 15 Strength saving throw or be knocked prone.

Fire Blood. A creature within 5 feet of the boar takes 5 (1d10) fire damage whenever the boar takes piercing or slashing damage.

Wrath Incarnate. The boar is immune to being grappled, prone, and restrained

Relentless (Recharges after a Short or Long Rest). If the boar would take damage that would reduce it to 0 hit points, it is reduced to 1 hit point instead.

Goring Tusk. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) piercing damage damage.

Lightning Breath (Recharge 5-6). The boar exhales lightning in a 15 foot cone. Each creature in that cone must make a DC 16 Dexterity saving throw, taking 66 (12D10) lightning damage on a failed save, or half as much damage on a successful one.

The boar can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The boar regains spent legendary actions at the start of its turn.

Detect. The boar makes a Wisdom (Perception) check.

Reckless Charge (Costs 3 Actions). The boar makes a charge trait action with advantage, everyone in the path of the charging boar can make either a flat Dexterity saving throw DC 18 or a Strength saving throw DC 18 with disadvantage, on a success the creature either avoids the damage (dexterity) or takes half damage and drops the boars speed to 0 until the end of its next turn.