4x Cass will reduce 80% damage for 3 turns. I dont think there is getting around this. Too late to nerf now after players have spent too much to get her.
What do you think should be done without really hurting the Cass owners?
Back on the real question by Bansky :"What do you think should be done without really hurting the Cass owners?", tbh i don't know, that's why my first response to developer feel so dissapointed bcs they break the game in just 1 year.
1. I don't know if nerfing not an option(but if they are not nerfing, 4 cassandra squad already nerf other type of squad)
2. maybe empower other thing(currently hero, equip or rune), for example imagine 4 resileince in 1 hero?, this is possible bcs even heirloom got skill in it also, but tbh i don't like this option either
3. Just bring new hero that can match 4 cassandra(i really don't like it, it just make VF like other traditional mobile game).
4. Improve Valiant significantly so they can mitigate dark lord a bit for example: give valiant on spawn skill that can reduce the OP-ness of 4 Cassandra into a super strong squad.
But still i can't give you the satisfaction answer, bcs the cassandra already in the level of OP, we're not mentioning how underwhelming of champion right now regarding arena(how they supposed to raise with the 4 cassandra on spawn skill?)