If I Summon a Villa, what happens? I am guessing this:
I gain Villa, which goes directly to my hand upon being gained, similar to Nomad Camp's ability.
I get +1 Action and return to my Action phase.
Summon tries to set Villa aside, looking for it in my hand.
At this point, I am not sure what should happen. On the one hand, maybe it succeeds, because even though my hand is not public information, everyone knows there is a Villa in my hand, and I am allowed to see all cards in my hand, so I can find it.
On the other hand, maybe it fails, because my hand is not public information, and in theory there could be some other ability that might trigger and cause me to discard or something, so in the interest of simplicity we consider it to immediately be lost track of when it enters my hand.
Edit: Actually, this seems similar to the situation where I Mine, say, Copper to Silver, and then reveal Watchtower to trash that Silver. We can do that, yes? In that case the Summon should succeed.