ARCANE BALLISTA

This enchanted ballista was created by Bartholomew Creedich, the former leader of the Slayers of Anaris. The ballista is considered a magical ranged weapon, with which the PCs are proficient. A creature manning the ballista can fire it as an action. After being fired, it cannot be used again until a creature uses an action to reload it.

Standard Bolt. Ranged Weapon Attack: +6 to hit, range 200/800 ft. Hit: 22 (4d10) piercing damage.

Net Shot. Ranged Weapon Attack: +6 to hit, range 150/600 ft. This specially crafted bolt unfurls into a weighted, iron-reinforced net upon being fired. A creature hit by a net shot has its speed reduced by half until the start of its next turn. In addition, it must succeed on a DC 15 Strength saving throw or be  grappled and falls prone. As an action, a creature can retry the saving throw, ending this effect on it on a success. 

Tether Shot. Ranged Weapon Attack: +6 to hit, range 100/200 ft. Hit: 11 (2d10) piercing damage.
This barbed bolt is attached to a nearby boulder by a sturdy chain. A creature hit by a tether shot takes becomes tethered to the boulder. While tethered, it is unable to move more than 200 feet away from it without first removing the bolt or breaking the chain.

please see ONCE MORE, WITH FEELING adventure created u/Adam-M