Dark Karma

Maybe through your years of study, your pure willingness to help others, or your desire to inflict pain, you learn to bend and twist the evil in others to your own will.  

Whenever a creature within 30 feet of you causes damage to one of your allies, you may use your reaction to cast this spell to lessen, and possibly redirect that damage to another target of your choice. 

Roll 1d10, and the damage that would've be done is reduced by up to the amount rolled.  If the damage that would've been taken is reduced to 0, you may redirect the full, original amount of the damage to another target of your choice.  This damage now becomes necrotic, and the new target must make a Constitution saving throw against your spell save DC.  On a success, the target takes half of the damage.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the amount of damage that can be lessened, and potentially redirected, increases by 1d10 for each slot level above 1st.