After flipping Thing in the Ice, Awoken Horror immediately cleans the board and presents a huge threat. Smoldering Egg's flipside is a 4/4 flier that shocks on every spell cast. This is stronger against midrange decks with lots of creatures that create value on ETB -- you'd much rather shock a Mulldrifter than bounce it. The body is also nearly impossible to chump, thanks to flying and the shocks, while Thing in the Ice has nothing to prevent chumping (by creatures entering after it flips). The flipside of the Egg is probably worse than Thing's, but both are very good, and the 0/4 frontside, which is much more relevant in the matchup, is the same.
A red Thing in the Ice. Clearly this is not a good card for an aggressive deck, but I think it could be very good in UR spells matter.
Since the flip condition is "Spells with total mana cost 7 or more", X-spells like Light up the Night or Tempt with Vengeance, expensive spells like Fact or Fiction and Memory Deluge, or alternative casting costs like a kicked Burst Lightning, flashbacked Firebolt or overloaded Mizzium Mortars let you flip this with relatively few spells cast (you still always need to spend the same amount of mana).
After flipping Thing in the Ice, Awoken Horror immediately cleans the board and presents a huge threat. Smoldering Egg's flipside is a 4/4 flier that shocks on every spell cast. This is stronger against midrange decks with lots of creatures that create value on ETB -- you'd much rather shock a Mulldrifter than bounce it. The body is also nearly impossible to chump, thanks to flying and the shocks, while Thing in the Ice has nothing to prevent chumping (by creatures entering after it flips). The flipside of the Egg is probably worse than Thing's, but both are very good, and the 0/4 frontside, which is much more relevant in the matchup, is the same.
I think this can be a good card, but it does have hard and deep competition in Young Pyromancer, Bloodthirsty Adversary, Magmatic Channeler and Abbot of Keral Keep, which are all go in more decks. I guess it's not worth it, but I'm posting a thread on it as I'm interested to see what others think.