Changing your appearance/form

Hey, guys i usualy see players changing their appearance, like blood elf looks like tauren or dwarf. How they do it ? And can only wars do this?

You seem to be talking about the http://wotlk.cavernoftime.com/item=50363 proc.
There are 3 procs: vyrukl with haste, iron dwarf with crit and tauren with str/ap;

Also, there might be some other fun things ingame that transform you, but I don't hunt those fun items so someone else might know more.

https://www.wowhead.com/item=35275/orb-of-the-sindorei
https://www.wowhead.com/item=43499/iron-boot-flask
https://www.wowhead.com/item=1973/orb-of-deception
https://www.wowhead.com/item=6657/sa...eviate-delight

Those just some the common ones :P there are soooooo many lol

can also be:
https://www.wowhead.com/spell=36897/...er-malfunction
caused by the transporter items used by engineers

Can u give me link or some info how i can learn more for items like those? I find them fun. Ty !

http://wotlk.cavernoftime.com/item=8529
Questline from Gadgetzan, Tanaris.

Where to find the items, googling is easy.

The murloc costume changed you into a murloc https://www.wowhead.com/item=33079/murloc-costume
The red Ogre costume https://www.wowhead.com/spell=30167/red-ogre-costume
The Magic eater fish turn you into basilisk, locust, whelp, or whisp https://www.wowhead.com/item=43572/magic-eater
The Underbelly elixir might not change you appearence, but it changes everyone elses https://www.wowhead.com/item=44012/underbelly-elixir

Then we have all the world events, like Halloween event which is in 4 days from now gives you wand that can transform yourself or people in your party to - lepper gnomes, Wisps, Skeletons, Pirate, bat, ninja and more.

There's tons of more that I cant think of right now like other world events, seen people turning into rabbits too.