Tempest devotion is usually very cool but often skipped in lightning builds. Their usual route is Spear+Ultos combo, for 2H builds even Ultos+Korvaak. I have used Tempest on Sorc build, where you can have 100% uptime of Reckless Tempest proc with Star Pact but it’s still pretty niche.
At same time Lightning retal is pretty niche as well and definitely lacking behind physical or acid. Gear gives some nice flat lightning/electrocute retal (mind difference between min and max value is pretty big) but there are not dedicated lightning retal devotions and it’s tough to convert other flat retal damage to lightning. So you are not getting much retal bonus and your devotion route is pretty generic like this one for example:
So my idea is to add lightning retal support to Tempest, that will be useful for this archetype and maybe can open some lightning hybrids opportunities
If you also take Rhowan’s Crown then it is not so far out of the way, and Chariot also takes 5 purple. But Tempest takes too many points and offers too little for most builds. You can always find an equally good solution with Spear.