Virulent Necrostrike (5e Spell)
From D&D Wiki
|Casting time:||1 bonus action|
|Duration:||Concentration, up to 1 minute|
The first time you hit with a melee weapon attack during this spell’s duration, your weapon flares with a sickly green energy, and the attack deals an extra 1d4 poison damage and 1d4 necrotic damage. Additionally, if the target is a creature, it must make a Constitution saving throw or have disadvantage on Strength checks and saving throws until the spell ends and reduce its AC in 1 until the end of your next turn.