Once you go Super-horse, you never go back!!
Lois, Lois,Lois. The ODDEST things do seem to happen to you on a regular basis. Weren't you a centaur for a while? And had monkey feet? And could breathe underwater? How can Superman even compete with that sort of thing?
This is, in fact, from that centaur story.It's like Lois was vulnerable to Red Kryptonite. And regularly wore jewelry made from it.
Aha! I should have known from the "unbreakable spell" hint. Turns out...it WAS breakable!
Super-Filly, Steed of Steel, Mare of Might... I don't understand why we never got a lot more super-horse stories.
They simply write themselves!
So now, instead of a bridal path, she can use a bridle path
Let's see: if Supergirl had been the one to become a horse, would she have been a palomino?