Probably a noob question, but can I use spirit leech on a cannon or other warmachine? The spell says "any model" but it seems strange that my slann is able to suck out a cannon's spirit. Or is it just resolved against a crewmember?
Yes you can as the cannon is a single model for all rules. So you target the cannon for rules purposes but in essance you would be sucking the life out of the crew (3 crew, 3 wounds). It was just made a single model for simplicity