My Breton battlemage just discovered the Atronach stone (+50 spell absorption)

I would like to know how activating this stone will have an effect on her inherent characteristics:

• Dragonskin : Absorb 50% of magicka from hostile spells for 60 seconds.
• Magic Resistance : Breton blood grants a 25% resistance to magic.

Does this mean if she activates the stone, she will get 100% spell absorption? what effect will that have on her active powers?
(I mean exactly how can the Atronach stone help during battles with mages for example...)

I read that Bretons can absorb spells "once a day"? What does this mean? Mages cast all sorts of spells in battle... does this mean the spell absorb will work only on the first spell cast and just for 60 seconds?

Does the Atronach stone give her a certain % resistance to magic? Am still a bit confused with resistance to magic and spell absorb...

Thanks for your replies!

Spell absorb works by entirely negating the damage a spell would deal to you, and instead converting it to Magicka for your use. Whereas magic resistance effects every single spell cast on you to a lesser degree, magicka absorb only works on a certain percentage of the spells cast on you (in the case of the Atronach Stone or Dragonskin, 50% of the spells cast on you). The Atronach Stone is always active, so it will always absorb 50% of the spells cast on you. If a spell isn't absorbed, your resistances would still lower the damage it deals. If you activate Dragonskin on top of the Atronach Stone, the effects would stack, but I'm not sure to what degree. I'd assume it'd be 100% spell absorb, but it might be 75%, in the fashion some stats work in a typical RPG.

Personally, I find the Atronach Stone to be one of the best in the game, especially for battle mages. Since you're casting less than a normal mage, the heavy loss of magicka regen isn't going to be as noticeable, and the increase in total magicka is very useful. The magicka absorb makes mages much easier to manage, as well.

my current PC is a briton. i mainly use dragonskin to protect against dragons. it does seem to reduce damage from dragon attacks. oh dragonskine can only be cast once a day.

right now i am using the lord stone for another 25% reistence against magic. i don't feel the need to resort to casting dragonskin as often.

the aetherial crown reward for the lost to the ages quest allows for two standing stones effects to be active.

it sounds like a PC can have 100% protection against magic. having the atronach stone active might cause problems with conjuration spells. but a patch might have corrected this.

Playing on XBOX the absorption of summons won't be fixed. I think the unofficial patch fixes that for PC users. So if you have 100% spell absorb, that's 100% chance of your atronach summon failing(and you absorbing it instead)

Dragonskin is a power you can use once a day. If you use it while you have the Atronach stone activated, you will absorb any spells for the duration of Dragonskin.

Also, the order matters : absorption comes first (and note that unlike resist, it's chance based, so 50% means you have 50% chance to completely block a spell and absorb it's base cost in magicka), then resist magic, and finally resist fire/frost/shock.