The ooze is the brown liquid leaking out and pouring down the side of the ruins, probably shaken loose by an earthquake or something
It relies on creature combat and chip damage to eventually win the game
All three options destroy multicolor decks
Here is how the list breaks down by price tier, based on average TCGplayer market prices: Under $10 (Budget Game Changers) Gamble, Crop Rotation, Fierce Guardianship (from precon reprints), Narset Parter of Veils, Underworld Breach, Opposition Agent, Biorhythm, Coalition Victory, Braids Cabal Minion, Gifts Ungiven, Panoptic Mirror
Getting all creatures for 2 mana is fantastic, be it in Standard or EDH, and I believe this white sorcery will find many homes
It's a great mana sink, it's a great long-game card, and it's fun for Jonnies to combo with as they blow the counters off with Giant Fan and similar effects