If you are having difficulty clearing the final stages: Beginner’s Strategy Guide to Challenge events
If you are looking for Strategies to Maximize your scores
Majority of Monsters: Green & Dark
There are not many synergistic Holy heroes for challenge events.
Ice heroes will not be as effective against the Nature Monsters in this stage.
Therefore you will want to bring Fire heroes.
Recommended Fire heroes
*Multiples of a single hero can be used.
**Heroes are planned for mono color usage – to maximize the chance to be able to clear the first wave of enemies with a good cascade of tiles. Alternative hero choices here