Melt is created when you pair Cryo with Pyro, which does 1.5 times the normal Cryo damage. And finally, combining Cryo with Geo creates Crystallize, generating a Cryo shard that creates a Cryo shield for your character. Which reactions work best for your team will depend on its makeup – for instance, you can combine Anemo, Cryo, and Hydro to freeze lots of enemies fast.