Disclamier: I don't own Avatar The Last Airbender and Avengers: Earth's Mightiest Heroes.
This is the story before the Season 6 of Winx Club.
Chapter 6 A Monster Of Fire Nation
At Fire Fountain City...
"KRAANG!"Said Kraang and then Captain America throw his shield and cut head of Kraang Droid.
"Hear me Kraang! I'm Thor the Thunderer, Prince of Asgard and this world is under my protection!"Said Thor and he's shoot lightning to the Kraang Droids.
"Kraang had to help Kraang to protect the mutagen bomb that was set to blow up by Kraang."Said Kraang
"Lotus Flower!"Said Flora and she's shoot it to the Kraang Droids.
"Lava Jab!"Said Bloom and she's shoot it to two HYDRA Dreadnoughts.
"Shining Punch!"Said Stella and she's shoot it to the Kraang Droids
Vision shoot laser from his forehead to the Kraang Droids. Master Splinter grab the Kraang Droid and throw to hit at another one.
"Hank we need you to make the bomb inactivated."Said Captain America
"No need it. Just send it to Microverse."Said Yellowjacket and he's shoot shriking laser to the mutagen bomb and shrink it to Microverse.
"Now the threat end."Said Yellowjacket
"Nice shot Pym."Said Ms. Marvel and she's throw the last HYDRA Dreadnought into the sea.
"Now let's take one of these to Tony to investigate."Said Captain America and he's pick up one of the broken Kraang Droid.
Later at Fire Nation Royal Palace...
"So what are these... Kraang?"Asked Katara
"The race of alien from Dimension X that try to conquer Earth."Said Donnie
"OUCH! It's bite me!"Said Sokka when the Kraang that he played with bite him.
"Bad brain! Bad Brain!"Said Sokka and he's throw it away.
"NOOOO!"Shouted Wasp and Donnie and Captain America jump out and grab it before it's escape.
"PHEW!"Said Donnie
"Hey look I'm Biotroid!"Said Aang when he took control over the Biotroid and he accident activate the butt cannon and shoot laser out and destroy the window.
"OOPS!"Said Aang
"So... what is this?"Asked Mai and she's gran the mutagen canister that filled with mutagen.
"Be careful about that Mai. It's called mutagen. It can transform you into mutant creature with the last animal that you contact with."Said Iron Man
"COOL!"Said Mai
"You will think it cool when you turn to be an ugly hideous monster like Mikey?"Asked Raph
"HEY!"Said Mikey
In the Beach Cave...
"Kraang found the lost mutagen canister that had been accident drop by Kraang now."Said Kraang and it's look at the mutagen canister and see that it was broken.
"The canister had been broken when it was drop by Kraang."Said Kraang
"Kraang still need the mutagen. So Kraang must have mutagen."Said Kraang
At that moment the the creature that crawl on the ceiling jump down to confron the Kraang.
"Contain it! Contain it!"Said Kraang and the creature grab Kraang Droid and throw to hit another two Kraang Droids.
"BRURA?!"
The creature walk out from the shadow and reveal to be giant cavehopper and it's grab the broken mutagen canister and look at it.
The creature walk out from the cave and jump in way that will lead it to Fire nation Capital City.
Dunring the way to go to Fire Nation Capital City. It's accident found the old torn robe with old red top hat and long green neckerchief.
So the creature attemp to wear them all and jump to the Fire Nation Capital City to find the place to rest.