Vorpal Strings

The space in a 15-foot radius centered on the chosen point is encompassed by barely visible arcane strings. The first time in a round when a creature moves at least 15 feet inside the area or makes a melee attack, it must succeed on a Dexterity saving throw, suffering 28 (5d10) slashing damage. This damage is considered magical for the sake of overcoming resistances. A Huge or larger creature makes this save with disadvantage.

The strings are barely visible. Any creature that can see the area can make a Wisdom (Perception) check or an Intelligence (investigation) check against your spell save DC. A creature that succeeds on these checks has advantage against the saving throws.

If a creature fails this save by 10 or more it automatically suffers max damage. If the creature isn’t size Huge or larger and doesn’t have Legendary Actions it must succeed on a Constitution saving throw or be decapitated.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d10 for each slot level above 4th.