Unholy Aura

Necrotic energy slithers out from you and coalesces in a dark essence in a 30-foot radius around you. Creatures of your choice in that radius when you cast this spell are enshrouded in shadowy tendrils and have advantage on all saving throws against spells cast by good-aligned creatures and creatures have disadvantage on attack rolls against them until the spell ends. In addition, when an attacker hits an affected creature with a melee attack, the attacker must succeed on a Constitution saving throw or the attacker's Strength score is reduced by (1d4). The attacker dies if this reduces its Strength to 0. Otherwise, the reduction lasts until the target finishes a Short or Long rest.