Proteus does more damage than she does and stops mana for 3 turns verses 25% mana reduction. Yes Carol should get 3 minions like Buddy or at the very least 1 for herself, but I think 3 would be ideal.
Some worry about stacking, but realistically it’s rare to be able to cast more than once or twice, sometimes you can get full mana and a diamond to cast twice and then it’s very unlikely you will be able to cast a third time before the bomb explodes. Most of the time you will be lucky to cast again by the time the bomb goes off the first time and most of the time you won’t be ready to cast again after 3 turns.
Heroes have become more powerful with season 3 and Carol being released months after season 3 should fall in line with season 3 heroes. Bombs can be cleansed and the damage isn’t much. I was very surprised she didn’t have minions, even Frosty gets all allies minions as a healer. I hope they look at this and add minion(s) to Carol, she badly needs them.