Ghost 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 10 (3d6) slashing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.

Incorporeal Jaunt. When the ghost boar moves, it becomes temporarily incorporeal. It can move through creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage and is pushed to the closest unoccupied space if it ends its turn inside an object.

Relentless (Recharges after a Short or Long Rest). If the boar takes 15 damage or less that would reduce it to 0 hp, it is reduced to 1 hp instead.

Tusk. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Tusk Swipe. When a creature hits the ghost boar with a melee weapon attack, the ghost boar can make one tusk attack against the creature. The ghost boar must see the attacker and be within 5 feet of it.