Finger of the Mountain (FotM) Empowered

Introduction

The Finger of the Mountain spell that you can receive as a reward from the Chorrol Mage's Guild as part of its Recommendation quest has always been a bit... lackluster, to say the least. It's got 2 main issues holding it back:

1) It's a leveled spell, which means, if you  do the quest at a low level - which is not uncommon, since Chorrol is right next to Weynon Priory, basically the first place the game sends you after leaving the sewers and thus a common place to interact with near the beginning of the game - you'll get a low-level version of the spell, which will end up becoming pretty useless as you get higher level, eclipsed by more powerful spells that you can buy or make.

2) The base magicka cost of higher-level versions of the spell become absolutely astronomical, so even if you do hold off on doing the quest until higher level to get a stronger version of the spell, it becomes increasingly difficult to cast, with costs rapidly exceeding what an equivalent spell made at a spellmaking altar would cost.

The quest makes it out to be some extraordinary and powerful spell, with Earana being willing to lie, cheat and steal to get access to the book that the secrets to the spell are contained within, and Teekeeus being convinced it's so dangerous it needs to be kept under lock and key at the Guild. Then you actually get the spell, and it's just... well, probably useless. You'll probably never cast it, because it's either just not that good or costs way too much magicka.

The Changes

I've seen a few other mods try to rebalance Finger of the Mountain, but none of them have been quite to my liking. I wanted the spell to both feel exceedingly powerful, as everyone involved in the quest seems to be implying it is, and also usable by pretty much any player, instead of just someone who goes extra far out of their way to compensate for the massive magicka cost. Trying to balance it in a way that made it strong enough to be worth using, but not spammable to the point of it being the only thing you use was pretty subjective, so I've decided to do 3 things to try to make it work:

1) I've changed it from a spell to a Greater Power. This has allowed me to make it much more powerful, without worrying about what exactly its magicka cost should be, or if it's going to be too good to the point of not using anything else. It also makes it seems more flavorfully usable by a character who isn't a dedicated mage - it's now just a cool lightning power you've received, not a specific spell that you're casting like any other spell. It can now be used once per day, at no cost. It is also immune to the effects of Spell Absorption and Reflect Spell, so you don't have to worry about your mighty once-per-day lightning bo