Elemental Shot

For the duration, all nonmagical arrows you touch become gain one of the Damage Types; Fire, Cold, lightning, Acid, or Thunder. For the duration, all arrows deal an additional 1d4 of the chosen damage type.

At Higher Levels. When you cast this spell using a spell slot of 3rd or 4th, the extra damage increases to 2d4. When you use a spell slot of 5th or 6th level, the extra damage increases to 3d4. When you use a spell slot of 7th level or higher, the extra damage increases to 4d4.

Edits: It is now working properly with the longbow Dragon's Bone.