Read the Jedit comics, and he largely comes across as a generic evil guy. His summons are mostly and outraight called a "red mage", so I assume he is primarily . With means (tyranny, illusion magic?); he even has some subtle solar motifs.

But what's in him, exactly?

Keep in mind that I haven't read Johan or Hazezon, I'm only familiar with the comic's light sith weirdo

Tell me more about Johan in the comic? In particular, what kind of red spells and critters does he employ?

Could be he was called a "red mage" in reference to his face paint.

Spams Beasts of Bogardan, for one thing.

Nope, he is because he uses mountain mana.

Sounds like old continuity strangeness. I believe Palladia-Mors was a red Primeval in the old comics, but her colors, according to the modern would indicate that she is green.