So, the Staff of the Magi, unlike other staves, has a listed save DC for a number of its abilities.
Normally, a staff uses the wielder's ability score modifier, but is this the case for the Staff of the Magi?
I know this question has been asked before and the general consensus is that the Staff of the Magi should follow the regular rules for staves, and that the listed DC's are simply a holdover from 3.5, but two things make me question this.
1. The Staff of the Magi is an Artifact, not in fact a "Magic Staff". It doesn't follow the listed rules for staves in that it has 50 charges instead of 10, and it uses a different recharge method. Aside from the fact that it has "Staff" in its name, it doesn't otherwise behave as a staff.
2. The Staff of the Magi was printed in Ultimate Equipment with no changes to its listed DC's. I'd have thought that Paizo would have taken the opportunity to correct this issue if it was in fact an error.