I have experienced several issues in several different arena runs since returning to the game. During several matches against druids my opponent always received both halves of choose cards despite not having any card that would allow this. I have also had Kaleegos not let the spell be cast for 0 on the turn it was cast. I have also had several freezes and Lags where I am booted back to the arena play screen with a game loss. The most egregious however just occurred where upon attempting to play my third match in my arena run the client just froze on looking for player. I then relaunched the client to find it had resigned my deck?! I am formally requesting reimbursement of some kind as I spent money on the arena bundle which portions of have been taken from me. If I do not hear back about anything I will unfortunately have to charge back all recent purchases and quit again.
Likely they DID play a card to allow this, and you just didn’t notice. Do you have a game replay recording?
I’m going to guess that you had already cast a spell on that turn, prior to playing Kalecgos. (Perhaps The Coin?)
No one on this forum can reimburse you for anything. You have to contact customer support, though I think your chances of success are still low