Spirit Explained

How does it work when a possessed piece is captured? I suppose that the piece is taken from the board together with the Spirit that was possessing it? I also suppose that this is the most evident explanation that will hold by default?

Without further explanation, I would think that the captured possessed enemy piece would take his/her/its companion Spirit with him/her/it.

The Defensive Metamorph has neither capturing nor moving ability.

The rule on Faerie-Interaction is that a piece that doesn't have capturing capabilities doesn't gain Knight-maneuver capture while being possessed; it can still move like a Knight. Simply not capture like one.

Since the Defensive Metamorph cannot move, does that mean it doesn't acquire Knight-movement either? Or, does the restriction mentioned in Faerie-Interaction only apply to capture?

Yes. I would count it as 1 capture that removes the possessed piece from the board. If we're playing crazyhouse, I guess the question would be whether you get 1 possessed piece or 1 unpossessed piece and a spirit. I would argue that the captured piece is still possessed, and thus would drop as a possessed piece if it were to return to the board, but I could see an argument that the spirit and the possessed piece should become separate when captured.

Short answer: I don't know.

If a piece has a rule that says it can't move, I would argue that the possessed piece still can't move like knight.

If a piece just lacks the ability to move, then an argument can be made that the possessed piece can move like a knight.

But in some sense it might be better to think about what makes more sense, rather than looking at semantics. I don't know the rules for the Defensive Metamorph, so I'd rather not answer.

We could add a rule for the spirit that it can't give knight movement to pieces that has no movement. Personally I don't think it makes sense for a spirit to be moving walls, flags, trees or whatever stationary pieces we might come up with.

Is there a game that gave rise to this question? If so, can I have the link?

I would agree with Martin that if the rule of the piece is that it can't move, even if it is possessed, it still can't move. Also, a defensive metamorph that moves like a knight would be way too strong of a piece, so as the inventor I would say a possessed defensive metamorph can not move.

@Marks1420 One of the two tournaments that are current hosts two first round games that countain two Spirits (replacing Knights) and two Metamorphs (starting on both Bulldog starting squares). It dawned on me that an allied Spirit might join in tactic and strategy with an allied Defensive Metamorph; leaving me wondering if the allied Spirit has the ability to endow it with Knight-movement.

I do agree with you that a Def, Metamorph being able to leap L is too powerful for a 10x8 board. I merely wanted to hear a confirmation from the authors.

And, thank you, @Martin0, for your elaborate response.

I don't think it makes sense for a Spirit to move a Stonewall or an Adobe Brick, either.

Ok, I'll update metamorph rules.