So, I have the following ice heroes at 3/70 and am debating who to take to 4/80 as I can only take one:
Currently, my maxed ice are:
I really don’t have an ice healer but do have healers in other colors (Delilah, Garnet, Vivica, Telluria)
I stopped feeding any heroes to Perseus as well as Richard.
Really looking to add depth to my ice mono team as well as for war.
Best,
B22
Loki!
The other 2 aren’t bad, but Loki greatly ups your versatility, enjoyment and effectiveness. You can always steal a Raffaelle or Frosth special if you really feel like you are missing out on them (you probably won’t, though)
Definitely Loki. He is probably the most versatile hero in the game, being able to copy any skill of your opponent’s heroes, including healing skills. And he is good against Alfrike which now is probably the scariest hero in rush wars 
I don’t have Loki so I am not completely sure, but as far as I understand, his main weakness is against Ninja heroes, as he copies just the first charge.
Second on my list would be Rafaelle. Frosth is also good, but his best is with other strong minion heroes like Bera or Freya or to help other heroes charge faster. But you already have 3 fast 5*
Lord Loki copies the Ninjas current charge, if the Ninja is at 0 or 1, it’s the first charge. So timing Lord Loki to get the 3rd Charge can be hard, other then that he is great. I have Loki at +20, love him, I steal whatever special I need at the time he’s ready, Alfrike, Yang Mai, Prof Lindenbrock, Ariel… you name it if you need a heal take it, if you want minions steal them. Just about anything you want you can take.
Just be careful not steal Alfrike a second time if she has Mindless attack on from the first steal… you’ll steal mindless attack instead… very annoying
What? That HAS to be a bug…
Copying mindless attack is annoying and worse it took me a few times to hammer that point home! 
Lord Loki by far. Loki can be the healer you want as well as an awesome Alfrike counter not to mention the fun factor.
Loki fo sho!
20 tricksters