bret said:
They list the difficulty in activating wands and scrolls with the UMD skill. Some would argue that since staff isn't listed, you can't do it. I don't happen to agree, but I can forsee someone making that argument.
Actually, they do list staffs. It's under the heading of
Use a Wand : "This use of the skill also applies to other spell trigger magic items, such as staffs." So, according to RAW, a Staff
can be activated by UMD (DC 20).
Since it states no where that it uses different rules then normal activations of a staff, the person with UMD would apply his own ability scores to the save DC, if higher than the staff's. You could up this with
Emulate an Ability Score, as far as I can tell. The ability in its strictest sense reads that you use it when you
need a higher ability score, but I don't see why you couldn't use it if you
wanted a higher score.
Upping effective caster level for Staffs is iffy at best. It's not really supported by the rules: Using a Staff is bunched in with wands. Since caster level isn't relevant for wands, the UMD skill completely ignores the issue. But...
You could argue that
Use a Wand is similar to
Use a Scroll. The latter one does give you an effective caster level (UMD result minus 20). Even
Use a Wand might give you a caster level, but it just doesn't matter for wands. (Hence, why they left it out). Effective caster level for staffs is (UMD result -20) seems reasonable. I think I'd allow it.
Fanog