Demona, the Gargoyle villainess herself, is one of the most valuable cards in Whispers in the Well in her enchanted version
The answer is If an effect puts a double-faced card onto the battlefield, and its front face can't be put onto the battlefield, it doesn't enter the battlefield
You will also want these to have a good curve, favoring cheaper creatures over pricier ones so you can put more onto the board quickly
(2025-06-06) If the target creature is an illegal target as Nibelheim Aflame tries to resolve, it won't resolve and none of its effects will happen
Each one reduces the cost of spells you cast that share a color with it, and they have passive abilities that feed into their own activated abilities
Anyway, it's nice to see a bunch of ice-themed environmental sorceries for Red as well