WoR, combined with the entire esper system, is why I've never been a huge fan of FF6. Honestly, the Tower of Fanatics is insanely dfficult. I used the Moogle Charm to get through it.

Of course, since I'm a perfectionist, I actually taught most of the spells to everyone by fighting Catuars, so admittedly I did more work than I needed to. Even still, I really didn't like the World of Ruin.