I concur with the existing comments - the rules could stand to be fleshed out significantly more, headings should be changed to be consistent with the norms of missions, and the entire mechanic of an objective becoming a model should be expanded (perhaps the objective-turned-unit should have a ranged attack that automatically targets the closest however many units, and removes spell tokens for each use?) As it stands, I think that a marker-turned-model remains a model the entire game (unless destroyed, but there's no reason to destroy them) and lose all spell tokens, but an argument could also be made for such a unit to remain controlled by the relevant player and completely able to have spell tokens used as normal. This would lead to it being in the best interest of a player to let the objectives grow in power after acquiring them, as they couldn't be stolen or contested that way.