Hm... You're right. I had been operating under limited information, as at the time that I was playing, I had never even opened the player's handbook. It was my first roleplaying experience and I was using a premade character with very little actual description of my abilites.

To answer the DC question.
I had 36 Int (+13), Spell Focus Transmutation, and Greater Spell Focus

In defense of myself abusing the system. The character was over a decade ago, and I knew very little about the system at the time. I was a friend of a friend who was handed a 20th level character. Not entirely the greatest experience, as I had to figure out the entire system as we went along, and had to contend with a 20th level wizard.