Bolster Undead 2014

You suffuse an area with negative energy to increase the difficulty of harming or affecting undead creatures.

Choose up to three undead creatures within range. When a targeted creature makes a saving throw against being turned or against spells or effects that deal radiant damage, the target has advantage on the saving throw.

When you cast this spell using a spell slot of 2nd level or higher, you can affect one additional undead creature for each slot level above 1st.