What is the plural of "staff"?

"Staff" as a collective noun meaning a body of people takes either a singular or plural verb depends on whether you're thinking of the body as a unit:

The staff is unanimously opposed to the dean's recommendation.

or as multiple individuals

All the staff were shocked by the dean's recommendation.

The plural of "staff" is "staffs," and when you talk about staffs, you're talking about separate bodies of people, which, of course, requires a plural verb:

The staffs of both colleges were supportive of the joint program.

Staffs, when you're talking about the staff of Office A and the staff of Office B.

If you are talking about the kind of staff that Gandalf carries, the plural is staves, which is a word I've always liked.