You can see the tank skins upon entering the vehicle depot. By default all of the skins are locked, unless you have obtained them during the quests. If you posses a tank skin you can change it and your appearance on the battlefield will be different.
The Red Baron tank skin was obtained during Winner Takes it All event, which took place between Days 2,835 and 2,841.
The Red Baron is a plasma shooting, death-defying tank which is sure to create some havoc on the battlefield. Get out there and shoot some plasma!
The Monster Grinder tank skin was obtained during Tales of the New World: Headless Horror event, which took place between Days 2,899 and 2,904. The rumor has it that Plato himself has used the Monster Grinder on his adventures. Those are some big shoes to fill! Can you handle the pressure?
The Mjolnir Tank was obtained from a weekly challenge during the Tanking Mayhem event. The weekly challenge took place between Days 2,989 and 2,996. With the Mjolnir Tank you can electrify your enemies and give a shocking performance on the battlefield! Pun intended.
The Manticore was obtained by thrivingly gathering an impressive amount of prestige points in the weekly challenge between Days 3,143 and 3,150. With the Manticore on the battlefield, your enemies will be fated to military doom. Get ready to make your opponents tremble in fear at the manticore's sight!