Mehrunes' Calling (Power) 1.0.0

What this mod does:

This mod adds a custom spell tome to the the interior of the Mehrunes Dagon shrine upon a pedestal.
The spell tome isn't a spell, it's a power.
This powers allows you to breathe fire to invoke a dremora from Oblivion at the cost of a humanoid dead body and magicka.
It doesn't deal damage to humans, though it will stagger them and also cause them to become hostile.

As a bonus, a spell tome has been added to the game that allows you to breathe fire that does do damage at the cost of magicka.

What I need help with:

Making the spell unavailable in shops
Changing the color of the summoning effect

Demonstration: