Oh hey, and welcome to the forum.
I hope you're enjoying Demon.
A standing SP restorer is probably pretty likely at some point.
100 SP abilities might be a bit tricky: the AI would have to be able to intelligently use them too, which can be very tricky with all-or-nothing abilities since it will be bad if a player ally uses one at a time the player feels like it shouldn't have, or holds back on it when the player wishes they wouldn't.
New elements, including possibly an "almighty" type like you suggest, is on the table.
There actually is an ability that reduces the Endure cooldown, though it is a rare one: Unconquerable. Each time you take damage, your Endure cooldown drops by 1 turn.
I think a certain unique in the upper half of the Tower is the most reliable source of this ability.
A passive that grants global speed is definitely possible, though it may be a fairly small increase if it isn't conditioned in some way.
Thanks for the suggestions.