Gargalesis

A stream of crackling, pink energy lances out toward a creature within range, forming a sustained arc of forked lightning between you and the target. Make a ranged spell attack against that creature. On a hit, the target must succeed on a Constitution saving throw or fall prone, becoming incapacitated with shrieking laughter and unable to stand up for the duration.

At the end of each of its turns, and each time it takes damage, the target can make another Constitution saving throw. The target has advantage on the saving throw if it's triggered by damage. On a success, the spell ends.