Something I can't make out from the core rules:

When the main players ask for allies, the other players can say yes or no. But who decides the number of ships that the allies contribute with?

For instance, if player A asks player B to be an ally, do they agree beforehand how many ships B will contribute with? If so - does B have to do as agreed?

If player A is not satisfied with the number of ships that B contributes with, can player A then call off the alliance and attack on his own? Or does player A have to take on B as an ally once player B has been asked and agreed to be an ally?

I'm asking because you might be reluctant to bring an ally with only one ship, whom you still have to share the win with...

Jumpingfrog said:

Ultimately the only thing the main players can control is who they invite. The allies are responsible for placing the ships and it follows that they can place any number they want under normal circumstances.

Jumpingfrog said:

I do not think an invitation can be conditional in a binding way and players cannot be uninvited. I think these would be significant enough that the rules would stiplify if this could be done. That being said, only placing one ship is kind of a **** move-- especially if you agreed verbally beforehand, though not as bad as asking for allies and then negotiating. Players tend to keep this in mind.

Once you place a ship into the encounter, you are committed, and cannot remove ships (nor add more).

A player decides how many ships he or she is committing on his or her behalf. The classic alien Crystal is what played around with that idea.

Only putting in one ship may seem like a half-hearted move, but keep in mind that player may now play reinforcements, as well as other cards (or power effects) that can affect the outcome.

On the other hand, once the other players start tossing in just one ship as an ally, you really start to wonder whether it's worth inviting them at all. And then you start thinking differently about alliances in Cosmic Encounter, and the game gets much more tactical and interesting!