I totally forgot about Ash Guardian, and since the spell targets the heart stone it won't trigger our spell absorption on console.

Oh, seriously!?  Awesome!  

Do you know off the top of your head if scroll-based summons get absorbed as well?  

No sorry never really use scrolls.  I would assume that they do since staves do. 

Don't forget about the Shalidor scrolls that Urag sends you to get.

I have been field testing this with my Nord (bite me, Altmers) and Conjuration scrolls do get absorbed with the Atronach Stone. I was tempted with the Apprentice Stone but the magic regeneration only works outside of combat. If I had the aetherial crown, I would opt for both the Atronach and the Tower Stones instead of the Lord Stone. BYMMV.

Ah, thanks for the confirmation.  

The Apprentice Stone *should* be increasing your regen both in and out of combat.  It just won't regen as quickly in-combat as out of it, but it will still increase faster than without the stone, if that makes sense.  

It doesn't increase it while you're in combat, only out of combat.
http://www.uesp.net/wiki/Skyrim:The_Apprentice_Stone

The incombat magicka regeneration is 1/3 of your base magicka regeneration.

Maybe or maybe not. I wouldn't take what UESP states like it was set in stone. Just because I did not see the blue bar fill up quickly in combat doesn't mean it didn't do the job. The Lady Stone fills both health and Stamina but you would only see the Stamina bar go up.

That said it is nothing a couple of regenerate magcika potions (garlic and salt piles are common enough to find) can't fix.

I'll provide my comments & critique in a bit. Just woke up. Expect some Long rants and comments. One thing I can help provide you a heads up though... I gotta "bone" to pick with necromancy. More on that later.

The uesp uses the creation kit to verify stats/mechanics. I take it like it's set in stone unless I know it the better.