Professor Codex Battle Secret:
In chapter 3-9, (Dracula's Castle) after you beat Dracula, there will be a cloaked figure behind him, which turns out to be - Professor Codex?
This is a tip for beating him:
Use the Aegis of Athena, the Hand of Hercules, and the Endless Gem Pouch. Then spell ~7 letter words and power them up to defeat the summoned bosses. When you battle Codex, spell words that are as long as you can, and don't be afraid to use scramble! Make sure you have around 10 of every potion, and after a while Codex will be finished!