In other words, your pokemon's status effects can activate outside of your turn
While a double-faced card isn't on the stack or battlefield, consider only the characteristics of its front face
For ones with three saga steps, you only get one chance to attack with the creature, but some are longer
And then theres the ability to draw cards from the bottom, which works well with lots of library manipulation spells
If the target land isn't destroyed by Sundering Eruption's effect (perhaps because the land has indestructible), its controller still gets to search for a basic land card, and creatures without flying still can't block this turn
Theres a possibility of finding a couple rare or mythic rare cards in a single booster and a guaranteed foil card