@Shalvenay
GM fiat is an action. Rulings-not-rules is an attitude that leans toward GM fiats and house rules over checking & staying faithful to source material. Rule of cool says "you're trying to use Grapple to pin the dragon's wings to its back; I don't think the rules let you do that
but it's awesome so I'm totally going to let you do that anyway." (the rules might actually let you do that, I'm just making that up for an example.)