I played a Shaman today and he had a Radiant Elemental on the board which reduces spell cost by one, and he had Unstable Evolution which is repeatable and only costs one mana.
So he just played the Unstable Evolution over and over again on a 1-1 minion until it turned into Malygos, then stopped.
Can a player just do this until their time runs out?
What is the limit to card cost? 10? So you get to 10 and then just keep getting different 10 cost minions over and over?