Some are rare by virtue of what they were in, perhaps an underprinted Secret Lair, like the Galaxy Staples
Locking out artifact mana, Chromatic Spheres, Expedition Maps, Engineered Explosives, Aether Vial, equipment, Oblivion Stone, and more, Collector Ouphe really is just a 2/2 Stony Silence
This is a deck that plays 17 lands (and may have been close to starting 16 lands) but chooses to board out a land for a 24th spell whenever its on the draw
Ba Sing Se Ba Sing Se, from Avatar: The Last Airbender , is a green utility land that enters untapped if you control a basic land (something a budget mana base can usually accomplish) and has earthbend 2: You turn one of your lands into a hasty creature with two +1/+1 counters, and it returns tapped if it dies/exiled
The requirement of eight different names among unlocked doors translates to just four fully unlocked Room cards, which is a lot more attainable than it might first appear
Any creature that comes under your control has summoning sickness the turn you obtain control of it, even if it was a non-creature permanent before becoming a creature (thats why even vehicle commanders have summoning sickness, too)