Necrostrike (5e Spell)
From D&D Wiki
|Casting time:||1 bonus action|
|Components:||V, S, M (a melee weapon)|
|Duration:||Concentration, up to 1 minute|
You fill the weapon used in casting with necrotic power. The next time you make an attack with this weapon in the duration of this spell, their hitpoint maximum is reduced by the damage you dealt with the attack. The hitpoint maximum reduction is undone upon finishing a long rest.
At Higher Levels. When cast at 2nd level or higher, your first hit deals an extra 1d8 necrotic damage for every level above 1st.