I'm in a hurry so just a quick glance at item selection.

You are trying too hard to shove your lane. Shyvana's Burnout is already an exceptional pushing tool, Hydra and Sunfire just feels like putting the smallest layer of the already huge icing on your cake. Randuin's Omen gives you much better stats and better active and passive.
And even Hextech Gunblade gives you better in every offensive stat you need than Ravenous Hydra, unless the enemy team has 5 squishies(Then you can ace them 1v5 with hydra).

She deals 75% magic and 25% physical damage, so Spell Vamp>Life steal.
Maxing E gives you much more damage due to the cdr you get from levels, and prolongs the time you do % damage.

21 offense is generally bad, flat AD is worse, not taking Block and Unyielding is the worst you can do with masteries.

I just tried the champion using this guide and I found it pretty helpful.

THE WALLS OF TEXT.
Oh also put the lore at the bottom or remove it. TRUST ME IT WILL HELP..

Thx for your help this is my first guide and because of you i tried to make this guide usefuller! I hope now it got more information in it and it can help a lot of you guys to get known to my favotire champion Shyvana

There is like... no information in this guide.

Also not too sure about Tiamat rush.

I will assume that is advertising.

I would definitely learn how to bbcode and I am new to Shyvana and don't know how to play her.. I would want a guide to help me become a boss with her.. I personally don't think this guide could het me there YET! With a little work maybe it could!
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Uhm you should give us more information.
For example: When its the best time for use ulti?

Lack of BBcode and some walls of text. Needs greater aesthetics.

Why not Greater Mark of hybrid Penetration because it fits her beautiful to her parted damage output and I suggest you to gor for Executioner in the Offense Tree (I would personally go for 21/9/0 or 9/21/0 anyways). Randuin's Omen is such an awesome item instead of Warmog's Armor in many situations and why not mentioning Blade of the Ruined King and a start option with Doran's Blade/ Shield?