Infinite Unstable Evolutions?

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?

Using an Unstable Evolution with a Radiant Elemental (or Sorcerer's Apprentice) will allow the player to repeatably use this combination until they evolved into a 12 cost minion or the player's turn ends due to time limit - whichever comes first.

If you are lucky enough to gain a Sorcerer's Apprentice or Radiant Elemental, you can evolve your other minions an almost unlimited amount of times (as you can't evolve them into anything higher than a 12-cost)