Part of Move
Some card effects specify movement to a specific location, typically by a triggered ability. For example Giant Shark, Mount Ussar Sanctuary, or Guardian Angel. Some spells also provide such an effect, e.g. Harpyon Urge. When resolving such an effect, the controller of the effect must specify a path that is the fewest possible steps to the destination. If there are multiple equally short paths, the controller chooses. If no such path exists, the unit doesn't move at all. See Range of Motion for how to apply lookahead when determining the path. Note that the basic abilities 'Move and Attack' and 'Defend' do not require the player to choose the shortest path to the destination because they are limited by the unit's movement (typically just a single step).