Secret Room – Overpowered Nerds
There is a secret room in a mission in Jungle. If you have missed it, it’s under Southern Temple cluster of missions. Overpowered Nerds. Anyhow, here’s a screenshot of the location. I’ve opened it already, so use the Big Crystal underneath as a point of reference to find the hidden door. You’ll find a chest there, and will have to fight 3 kids.