Circle of Shame is pretty good. I also like Tebien Sublimator, but I don't understand its usefulness as of yet.
Mechanically, Tebian Sublimator is meant to connect to Dominaria block and monowhite Kaldarjar-faction decks in particular. Basically, he turns all of your snow-colored creatures white (in addition to your artifacts and lands, obviously.) Starting with these cards here in this thread, I'm planning to have a bit of a "white matters" subtheme going on in Eleventh Edition, and I want the white Kaldarjar decks that are running colorless cards to be able to make use of this theme, if they want to.
Flavor-wise, I'm doing a little bit of forward projecting to Mongseng, Khanar, or wherever the heck Sarkhan Vol's Mongolian-themed plane ends up being, and creating the Tebien as a race of intelligence, frozen-desert-dwelling dudes modeled after Bactrian camels. So I'm also going for a bit of a flavor connection to the snow faction, as well.
Blinding Light is a solid choice for a reprint, and I agree on the rarity change.
The Sublimator I don't know about. He's useless offensively and his ability, if it's relevant, is difficult to shut off for 3 of the other 4 colors due to his body. It's also rather inelegant as worded. Would a half Eight-and-a-Half-Tails do the trick? ":1mana:: Target creature you control becomes white until end of turn." reads a lot more grokkably than the current wording, especially with Blinding Light going on.
Walk of Shame is a great playtest name. White doesn't get a ton of flash, but I do like it as a way to make a narrower O-ring variant more palatable. I might also accept gaining life equal to the card's converted mana cost.
Walk of Shame is great. One of the main problems with Oblivion Ring is that it doesn't do anything against combo decks that can win in one turn (Splinter Twin in Modern for example). This would be a great card to have if it was real.