Defend! Great Treasure Operation is the eighteenth episode of Zoids: Wild. It first aired in Japan on November 3, 2018.
This episode is character development for Sauce, the female member of Team Supreme.
The episode starts out with the Freedom Trio being attacked by Sauce, who is initially unaware of who they are. When she realises (and is introduced to Onigiri/Penne) she takes them back to a small village where she's staying.
They talk for a bit, and think they might have some leads to the Great Ancient Treasure Z. But eventually the village is attacked by the 3 Death Metal Raptor leaders from early episodes (with Arashi forgetting who they are)
The three attack using formations "A", "B", "C" etc. And take Penne/Onigiri by surprise when they bypass the liger and attack them instead. Though they are repelled, the retreat using Formation "N" - "look over there".
As the others go back, there's some friction between the Freedom members on how they should do things. Arashi wants to charge in, while the others want a more reasonable approach. Sauce tells them a bit of backstory about Team Supreme, when they started out they also had a lot of disagreements, but with Bacon as their leader, they managed to make it work out.
Arashi, inspired by the story, tries to appoint a leader for their group, which causes more problems than it solves. As a compromise, he decides to appoint everyone as a leader. He's the "charge in" Leader, Penne's the "One hit special move KO" Leader, and Onigiri is the "Genius" Leader.
When the Death Metal guys come back, they are quickly dispatched by team Freedom's new tactics.
They resort to their final formation. It's not a letter and is instead a surprise bomb attack to drop boulders onto the village.
Arashi uses his Wild Blast and blocks one rock.
Then we see Sauce use her Kabtor's Wild Blast for the first time.
Kuroame then shows up and also uses the Grachiosaurus's Wild Blast.
The episode ends with the old couple in the village revealing they had no info about the Great Ancient Treasure Z, and instead were excited by the birth of a newborn baby.
Post credits shows the Death Rex once again bound by chains and the leader of Death Metal being handed a key for a Death Blast.