Grim Scythe

As a bonus action, for
1 minute, a spectral blade forms on the end of a quarterstaff you touch.
While this blade lasts, you use your spellcasting ability instead of Strength for the attack and
damage rolls of two handed melee attacks.
The weapon also becomes magical, it deals
necrotic damage instead of bludgeoning,
and it's damage die becomes a d10.
The spell ends if you cast it again or if
you let go of the weapon.