Vorpal Blade

Weapon (any slashing), very rare

This +1 sword has three small diamonds encrusted on its base. Whenever you make an attack roll with this weapon and roll a natural 18-20, it is an automatic hit. If you rolled a natural 20, the Vorpal Blade deals extra damage equal to 1d4+1d6+1d8+1d10. Any creature that takes damage from this weapon cannot use regeneration on its next turn.