Spells mod does a number of things, including making it a lot harder for people to do Wrathful Skies. Also makes other spells (Army of Lead & Gold, Legions of Steel) somewhat easier.
Summonings, the elemental royalty (and I think the unique devils) are harder to obtain, while a lot of the others that don't get used much were improved.
I wouldn't mind, especially as the same pretenders can be used, and it helps tame Caelum if only a little bit.
