The magic item rob of absorption
… absorb a spell that is targeting only you and not with an
area of effect.
Although the Staff of the Magi only states
… when another creature casts
a spell that targets only you
and nothing else
Does this mean the Staff of the Magi can absorb area of effect spells as long as it is only targeting the individual who wields the Staff.
For example if fire storm was cast against a party the item wielder could not absorb the spell but if the item wielder alone was being affected they could absorb the spell.
Best Answer
Let's look at the staff again (emphasis mine):
STAFF OF THE MAGI (DMG, pg 203)
Looking at Fire Storm (for example, again emphasis mine):
That, to me, reads as though you are not targeting a creature but an area. You can use that spell just to burn down a forest if you wish. No real target.
I think that the staff and the spell work the same in that regard.
If you look at a few other spells:
It should not work with those, but these:
Some tricky ones:
or other single target spells that target others at higher levels.
RAW: I don't really know for those, and I don't think there is a concrete answer. Someone should ask the game developers.
My Thought: With these tricky ones, the part of the spell that targets the holder of said staff could be absorbed. Those do specifically say that they target a creature, so they are eligible for absorption. A DM could possibly say that it absorbs the whole spell (including the parts not targeting the wielder of the weapon). As a DM, I'd allow the wielder the chance to absorb the part of the spell that targeted him. I think these just come down to the DM.