Like most Magic: The Gathering cards, the value of Cemetery Prowler depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Innistrad: Crimson Vow)
Sure Ancestral Mask is good, but Idolized includes everything from treasures to creatures to who knows what else, for a mana less
The aesthetic of cards in the Yu-Gi-Oh
If you have a way to control the top of your library, you can cast your Auras and Equipment without needing to actually draw them
You can carry 4 decks at a time, and more of your creations can be saved in the Deck Save Machine located at Dr
Which is all well and good, except one thing: R&D has it's own little sub-rules about this: A Creatures come before non-creatures