Weird family metaphors aside, when should you play 18 lands over 17
There are ways to answer Westvale Abbey // Ormendahl, Profane Prince once he kills everyone in the Abbey and comes out to play, but they are limited
Drawing 6, 9, or even 12 extra cards by turn 3 or 4 allowed Blue to simply overwhelm opponents with resources
Outlaws of Thunder Junction gave us the Greave's at home version in Lavaspur Boots, thankfully the power boost helps offset how much worse ward is as a targeting-deterrent, but it's still several notches below the other two
It makes all your artifacts indestructible, which locks opponents out of most interactionespecially useful for decks built around artifact synergy or combos
This card will shine most prominently in non-singleton formats like Explorer, allowing the player to run multiple copies of Fog in their deck, recurring the effect as many times as they can cast copies of the card