I loved the variety of material you explained in the guide, including the section about season three, and how you explained Dr. Mundo's abilities! Good reasoning throughout the guide, and great use of bb-code! :) With that said, here are my suggestions:
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• You used columns in your abilities chapter, your Pros & Cons chapter, and your Match-ups chapter. I really liked that, but I wanted more... There are no additional images besides the icons in the bb-code. I feel that it would be much more interesting to read the guide if it contained more graphics and formatting to spice it up.
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• You have some unnecessary / extra words in places throughout the guide, and some of your word choice is... unique. I would suggest copy pasting the text from the guide into a word processor to help you find some spelling / grammar errors. Some may not show up though, as word processors don't always correct grammar smartly, so feel free to PM me afterwards to get some help proofreading.
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• Additionally (and let me know if this is the case), your word choice (example: drake instead of dragon) seems different from that of the NA Server... If you play on the NA server I would suggest changing your phrasing to match the common slang used there. If you play on a different server, then I do not know what the preferred shorthand for stuff is.
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• I would suggest reading the guide over again and more thoroughly updating it to match the season 3 changes (you mention Heart of Gold once, and it would help readers if the material were already updated throughout, instead of having a separate chapter to discuss the changes). Additionally, consider getting a Rejuvenation Bead early instead of the Crystalline Flask as the Bead builds into Warmog's Armor which you use later. This will save some gold in your build. I do not know if this is best, so correct me if the flask is actually important for Dr. Mundo. I just feel that the mana regeneration is wasted on Dr. Mundo.
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• You did a great job with the colors where you used them, but consider using more colors to highlight key ideas in your paragraphs. As it is, the wall of text with bb-code interrupting it here and there will not communicate your ideas as clearly as it would with the extra colors.

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Again, great job so far! I think that with some added formatting and graphics, your guide will be top rating material!

Waiting to rate because I feel that you would get a much better score if you made some of the above changes. PM me when you are ready.

I'm going to wait to up-vote until you have fixed the word problems, and added some more colors or graphics or formatting. PM me if you have any questions :)