Artym's Morally Ambiguous Beam

You fire a beam of radiating green energy at a creature you can see within range. Make a ranged spell attack against the target, on a hit the creature takes 2d6 radiant damage and must make a Constitution saving throw, on a failed save the creature gains a point of exhaustion, on a success the creature is immune to the exhaustion effect of this spell until the end of your next turn. If the target is covered in metal or wearing heavy armor it makes the save with advantage. 

If a creature is immune to radiant damage, it is immune to all of the effects of this spell.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the radiant damage increases by 2d6 for each slot level above 1st.