Attack of The Mega Shredder!

"Attack of The Mega Shredder!" is the 21st episode in season 3 and the 73th episode overall. It aired on August 16th, 2015.

Official Description
Leonardo decides to sneak into Shredder's lair alone, and winds up facing the biggest mutant threat yet.

Characters

 * Leonardo
 * Donatello
 * Raphael
 * Michelangelo
 * Splinter
 * April O' Neil
 * Casey Jones
 * Karai
 * Shredder
 * Tiger Claw
 * Stockman Fly
 * Bebop
 * Rocksteady
 * Fishface
 * Rahzar
 * Shredder Mutants
 * The Foot Bots

Trivia

 * Last appearance of the Shredder Mutants.
 * First and only appearance of Mega Shredder
 * The Shredder Mutants mutated into Mega Shredder.
 * Leo wears his outfit from Vision Quest.
 * Raph injures his leg in this episode.
 * The Turtle Mech is used again for the 2nd time
 * This is the first time Casey helps fight in the Turtle Mech.
 * Mega Shredder is the first mutant to be made from other mutants.
 * The episode's title is a reference to the manga and anime series Attack on Titan.
 * When Leo and Mikey attack Mega Shredder, they improvise their Grappling Hooks in a manner resembling the ODM gear used by Scouts in Attack on Titan, specially when Leo is on his own using both his and Mikey's grappling hooks and his swords to attack Mega Shredder.
 * The scales on Mega Shredder's back are identical to Godzilla's. The music playing during Mega Shredder's appearance are also very similar to the original Godzilla's sountrack.
 * Mega Shredder's brain is located on his tongue, which is in the form of a young Oroku Saki, proving Stockman used Saki's DNA to create the Shredder Mutants.
 * Mega Shredder's tongue strongly resembles the awaken form of Ophelia from the manga series Claymore.
 * The Mega Shredder fighting the Turtle Mech is a reference to the classic Giant Robot Vs. Giant Monster theme used mostly in Japanese TV series and cartoons.
 * Mega Shredder has a green face with yellow eyes resembling the moon from "The Legend of Zelda: Majora's Mask".