It shoud be 
instead of 
, as a lighting rod is connected to the earth to make the thunders hit them. Gravity isn't what makes thungers fall, it's earth + electric charge.
Also, you can make it 1|0 cost and also protect permanents!
True, however Gravity is also the element of attraction, of collecting small things into something bigger, of devouring. Everything that is pulling something towards it, it can be considered 'gravity', so it is well fitted in the
element IMO.
By the way, I also think it is a little UP. Let's compare it with ES|JS or RS|MS, since they are the only cards in the game with anti-spell mechanic. They reflect the damage back at opponent and provide DR (except RS), let alone they stay forever and cannot be destroyed/stolen. However, they don't protect creatures like Finial does. Personally, I think you should be healed by the amount of the spell damage dealt in order to do Finial a competitive card.
