But, I feel like something needs to be done about Conjurer's Calling in Arena. There are a number of ways to deal with it in Constructed, but removal in Arena is hard to come by. When you leave even a single big minion up, it can trade with the opponent's minion and then multiply for only a measly cost of 3 mana, TWICE. It sucks losing to it because you can't play around it, even if you trade minions for the whole match. I don't want the whole class to die off like Druid or Warrior. Maybe reduce the occurrence rate?
I absolutely love that card and I haven´t played arena this season yet, but I can understand your concern and I think it´s quite possible that at least the pick rate for this card will be lowered, because I can imagine it being very strong in arena.
I am all up for it's removal. It's not healthy for the arena. Basically when you play vs mage, every 4+ cost minion of them has taunt. Ugh. It is absolutely insane with Nerubian Prophet, Even without twinspell it would be a very strong card. With twinspell, it's just broken.
Buff the occurence rate for other mage's cards if you want.