Multiattack. The hart makes a Lightning Antlers attack and a Thunder Hooves attack.

Lightning Antlers. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 16 (2d10 + 5) lightning damage. If the target is a creature, it must succeed on a DC 16 Constitution saving throw or have the stunned condition until the start of the hart's next turn.

Thunder Hooves. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) thunder damage.

Entangling Growth. Immediately after a creature the hart can see within 120 feet of itself hits it with an attack roll, the hart reduces the damage to itself by half. The attacker must immediately make a DC 16 Strength saving throw as beanstalks coil around it in its space. On a failed save, the creature has the grappled condition (escape DC 16) and has the restrained condition as long as it is grappled. The beanstalks vanish after 1 minute, if the hart has the incapacitated condition, or when the hart dies.

Lightning Call. In response to making a saving throw, the hart calls down a bolt of lightning that targets a creature it can see within 120 feet of itself. The target must make a DC 16 Dexterity saving throw, taking 19 (3d12) lightning damage on a failed save, or half as much damage on a successful one.