Better ways to proliferate without paying so much mana include Yawgmoth, Thran Physician or casting a low-cost sorcery like Thirsting Roots
Most people run 3 Cliffs however I think Im happy with the fourth copy
Most restricted cards arent consistent enough to build entire decks around by themselveswin conditions like Time Vault and Tinker being the exceptions to that rulebut they find their way into most decks, where they play a critical role in how those decks perform
ARC-V [edit] "Abyss Actor - Super Producer" and "Yosenju Sabu", based on Sylvio Sawatari
Later, once we established that the Knight deck would be about Equipment, this card became key for that deck as well
But in Japanese, its the Level Stealer, a master thief who doesnt have so much of an appetite