Frostmarch is a rare quest where you can obtain a warm cape and a farsighted telescope. These are essential ascension mats for 4* and 5* blue heroes.
To the new(er) players: complete as much as you can, it is okay if the last stage is too much.
To the advanced players: gets those mats!
The bosses are Ice Burrowers: one of them does a special skill Furious Bite which deals 235% damage to a single enemy and the other does a special skill Blizzard which deals 92% damage to all enemies and all enemies get -18% defense for 6 turns; and an Epic Rock Elemental who’s special skill is also Blizzard with the same damage and ailment.
Strongly suggest bringing a lot of green heroes. Berden, Brienne in the 3* tier would be examples. Caedmon and Melendor would be 4* examples.
@General_Confusion made a great point about the last rare quest that antidotes would be a good idea to bring and that would apply to this quest too. Just to get rid of that pesky -18% defense. Hope everyone completes all stages!