Warding Spirit

You may touch a willing creature. The creature's AC is calculated substituting your casting modifier in place of their dexterity if your casting modifier is higher until the spell ends. Whenever a creature damages the target of the ward, you may have them take 2 (1d3 or 1d4-1 minimum 1) radiant damage.

The spell's damage increases to 1d4+1 at level 10, and 2d4+1 at level 16