What are the rules for trying to banish an ally spirit? In a normal banishing test, net hits reduce the number of services a spirit owes its summoner, but in the case of an ally, there is no quantification for the number of services.

So how does this work in game terms? Does a magician try to banish an ally spirit using the same rules for banishing free spirits, i.e. using its unspent Edge instead of owed services?

If an ally is banished, does it simply wander off, or does it vanish for a time, as though it was disrupted? I am also assuming that disruption affect allies just like it does standard spirits?

Is it possible to destroy an ally spirit or somehow sever its ties with its summoner so that it can be summoned or bound by another magician? This is assuming the other magician does not have a copy of the ally's spirit formula. I'd like to think that an ally is permanently bound to its summoner unless someone undertakes a metaplanar quest to the ally's home with a copy of the ally's spirit formula and destroys the spirit for good, or if the summoner is killed or incapacitated and the ally breaks free. Correct me if I am wrong.

Banishing Free Spirits, which don't have any services, lose Edge points as explained in 109 Street Magic. I would go by that for ally spirits as well.

I can't find anything on how much Edge an ally spirit has, so I would give it Edge equal to its Force, given that that's what every spirit in the core book seems to have.

So because of Banishing Resistance, which gives extra services equal to its Edge, I'd require a number of successes to banish an ally spirit equal to twice Edge, which is equal to twice its Force.

I can't find anything specific or absolute, but given what's available, that's my suggestion.

Street Magic says allies start with the same Edge attribute their summoner has when the ally is first summoned.

I'd like to think the rules for banishing an ally are similar to trying to banish a free spirit, but there's bound to be differences. For example, as a bound spirit, an ally would roll their Force + summoner's Magic in the opposed banishing test, but a free spirit, lacking a master, would roll only its Force.

Also, if a free spirit's Edge is reduced to 0 by banishing attempts, it is temporarily disrupted and vanishes to its metaplane until its Edge refreshes (This I gather is completely different than a-spirit's-condition-monitor-is-full kind of disruption). So if an ally's Edge is reduced to 0 in this same manner, what happens to it? Is it "temporarily disrupted" in the same manner as a free spirit, or does its bond with its summoner prevent this sort of disruption from occurring?