Which episode of TMNT has a comic book writer with a crystal pen?

Question

I'm trying to remember an old episode where there's an author who straps a crystal to his pen and what he draws becomes real. He draws another dimension, the turtles end up there and there's some sort of fight.

Answer 1

This was (originally) a comic, the sole issue of the Donatello: Teenage Mutant Ninja Turtle micro-series, titled Kirby and the Warp Crystal

Kirby turns to see the turtle, and remarks that he doesn't remember drawing him and assumes that Don is an alien who has come to retrieve the "magic crystal." Don calms Kirby down and asks how he made the drawing come to life. Kirby explains that he found the crystal in a pile of coal and accidentally discovered its powers. The artist allows Donatello to try it out, and the Turtle draws a stick figure which leaps to life and promptly disappears. Kirby explains that all of the drawings made with the crystal-enhanced pencil come to life, only to disappear a few seconds later... all save for one, at least.

It was adapted into a 2003 animated episode of TMNT called "The King".

The man comments that he doesn't remember drawing Don and then assumes that the ninja has come to retrieve the "magic" crystal that allows the drawings to spring to life. Donatello assures Kirby that he hasn't come for the crystal, but he asks where it came from. Kirby explains that he found the gem in a pile of coal the other day and decided to attach to his pencil. Since then, everything Kirby draws comes to life (and Kirby draws a lot of things)! The amicable artist hands Donatello the pencil and tells him to try it. The Turtle agrees and draws a stick figure, which leaps off of the page and then attacks Don by kicking him in the shins. The mutant is not amused by this and he readies his bo staff - the annoying little stickman backs off and then zaps out of existence. Kirby explains that this happens to all of his drawings, they come to life and then quickly disappear.