Arcane Ballista

Magic Resistance. The arcane ballista has advantage on saving throws against spells and other magical effects.

Magic Weapons. The arcane ballista's weapon attacks are magical.

Siege Monster. The arcane ballista deals double damage to objects and structures.

Arcane Shot (3/Day). As a bonus action, when the arcane ballista hits a target with a ranged weapon attack, it can choose one from the following three effects:

1. Bursting Bolt. The target and all other creatures within 15 feet of it take an extra 10 (3d6) force damage each and must succeed on a DC 16 Strength saving throw or be knocked prone.
2. Flaming Bolt. The target takes an extra 11 (2d10) fire damage and catches fire; until someone takes an action to douse the fire, the creature takes 5 (1d10) fire damage at the start of each of its turns.
3. Thunder Bolt. If the target is a creature, it takes an extra 10 (3d6) thunder damage and the creature must succeed on a DC 16 Constitution saving throw or be stunned until the start of the arcane ballista's next turn.

Multiattack. The arcane ballista makes two arcane bolt attacks.

Arcane Bolt. Melee or Ranged Weapon Attack: +8 to hit, reach 5 ft. or range 100/400 ft., one target. Hit: 20 (3d10 + 4) piercing damage.

Lightning Bolt (1/Day). The arcane ballista shoots a line of lightning that is 120 feet long and 5 feet wide. Each creature in that line must succeed on a DC 16 Dexterity saving throw, taking 54 (12d8) lightning damage on a failed save, or half as much damage on a successful one.