Ok, so any help would be great. I have beat the original Panzer Hydra .... 100 times now. Still have not unlocked the next level :/ I got the rewards etc, just .... nothing new unlocked.

Pet in use is a Tier 5, am I missing something or is the unlock seriously THIS random? LOL Thanks for any help.

You need to use the medal from your achievement prize to unlock the next challenger. You need to beat each challenger only 10 times to get the achievement and medal/ trophy or whatever it is called :D

Beating the hydra ten times should have awarded a Brass Panzer Hydra Medal to your inventory for completing the achievement. You can click on it and use it to unlock the next challenger.

Arggggggggggggg ... ok, then im just out cause I clicked on it, didnt see any obvious options for a "real" use, so I sold the damn thing. shoots self in foot Thank you for telling me. I cant move on but at least I can keep my sanity now LOL

EDIT Just bought one for 15 mill LESS than mine sold for, unlocked and moving on. (wasnt sure if buying one would work, had to try!) Thank you both so much!!

They did say that they would make the medals available later... You could try filing a ticket & maybe you can work something out. The worst they can do is say "no" which just leaves you no worse off than you are now.

I'm glad to hear it all worked out for you. Enjoy your battles :D