This is a list of currently working codes. Some of the following codes are unlimited either found as a secret code from patch notes or hidden within the release trailer of certain updates. Codes can be redeemed here.
6Q6X-DD3Z-3MWN-6LWL-66XE: Salt Sower
MPJ7-LFWP-P7FF-Y9QW-GF6Q: Hexflame Harrier
7XRG-FPHE-Y7XZ-NL7E-NYN9: Sanctuary Shuttle
TROVESTAYSAFE: Tannenbomber’s Bell
You can get promo flux here
Additionally players can get a Sageosaurus code by creating an account at Trovesaurus and redeeming the code here.