I've gotten confused more than once because the artworks of Firestorm and Wall of Fire are too similar and difficult to distinguish on a tablet or small screen.
There's actually a lot of similar-seeming card artwork (probably because there're a lot of similar cards). Agree that further differentiation would make the game play a bit better.
Once I had both of these cards in my hand. I meant to cast Wall of Fire and ended up casting Firestorm. The carnage...