It absorbs My conjuration spells. It should only absorb my enemies incoming hostile spells, imo. And needs to be fixed.
Specifically, the "Absorb" ability (either from the stone, or perk) also has a chance to absorb your "Conjure Atronach/Dremora/etc" spells.
If you want to use conjuration and absorb, stick to bound weapons and reanimate spells - they're if I remember correctly.
-HK