Cull The Weak

When you cast this spell, you use some of your strength in the process. As a part of casting this spell you deal 1d10 damage to yourself as you summon the dark energy needed to draw the life from your enemy. Pitch black energy surrounds your hands allowing you to make a melee touch attack against one creature in range. If you hit, the necromatic energy seeps into the creature's body dealing 2d10 necrotic damage. If said target is killed by this attack, the creature's strength is drawn into you giving you 10% of it’s maximum hit points (minimum 1, round down) that can either be added to your maximum or to one other creature within 30ft of you. 

At higher levels, the damage increases by 1d10 and the percentage of maximum hit points you can distribute increases by 5% for every slot above 1st.