This is a skill you will slot but rarely (if ever) use.
It increases your max magicka by 5% for slotting it, plus if you have all your Mages’ Guild passives, another 2% max magicka and 2% recovery. Make it a priority to slot it on both bars. Note it grants Major Prophecy (increase spell crit dmg 2191), which will also apply to your healing. Keep in mind, Essence of Spell Power also grants Major Prophecy, which means if you can always slot Inner Light on both bars, you can run the 2-trait pots with only Major Sorcery and Major Intellect (made with lady’s smock and cornflower).
Thank you to Harven for a wonderful little add-on that lets you see different morphs of a skill. Super handy!