Decapistrate

You hurl a pulse of dark energy at a creature within range, attempting to both decapitate and defenestrate them simultaneously. The target must make a Dexterity saving throw. On a failed save, the target suffers the following effects:

• The target takes 5d6 necrotic damage and 5d6 force damage.
• If the total damage dealt exceeds the target's hit points, its head is severed from its body, causing instant death. If the target is immune to this effect or has legendary resistance, it instead suffers an additional 4d6 force damage.
• If the target is adjacent to a window or similar opening, it is forcibly propelled through the opening, falling to the ground below (if any).

On a successful save, the target takes half damage, and the decapitation and defenestration effects are negated.

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the necrotic and force damage increases by 1d6 for each slot level above 4th.