Bone Trap

Sprinkling the dust over an arm or leg bone of a dead creature, dark runes glow on its surface then disappear. When any creature, other than you, touches the bone, it explodes in a blast of black and purple energy. Every creature within 30ft of the bone must make a constitution saving throw or take 4d12 necrotic damage, halved on a success. Additionally, on a failure, a creature takes a level of exhaustion.

When cast at a higher level, the damage increases by 1d12 per spell level.