Chain Decimation

Upon casting, a crackling bolt of energy travels down the caster's body from head to foot, then splits to shoot out at any humanoid or fiend within a 20' radius.

All targets must make a Constitution saving throw. The target takes 10d10 force damage on a failed save, or half as much on a successful one. On a failed save, the bolt of energy continues from the target's body to hit any humanoid or fiend within a 10' radius; this happens regardless of whether the original target is alive or dead. New targets must make the same saving throw and take the same damage. On a failed save, the bolt continues to any humanoid or fiend within a 10' radius. The chain continues indefinitely until there are no more targets in range or every target succeeds on the saving throw.

If the caster is a humanoid or fiend, the caster is included in the area of effect and must also make the saving throw.