I didn't really read the adventure, just the monster combos, but it seems really... random. Demons, and then undead, and then lots and lots of cold guys.
Also, this adventure has what, 5 solos in it? It looks like a real slog. The Desecration looks like the most boring, annoying solo I've seen thusfar.
The Frostfury trolls make me weep. Those are brutal.
Koliada's statblock doesn't designate what happens when someone is incased in Koliada's Ice. Is it a save ends condition? Are they still restrained? Etc.
I find it interesting that aside from the trolls and treants, both of which are naturally vulnerable to fire, none of the ice monsters are vulnerable to fire. I know that the 4e philosophy doesn't want to stack immunities/vulnerabilities, but I knwo that it would at least irk the hell out of one of my players that something that resists Cold is not vulnerable to Fire (he made the same complaint over fire/magma monsters when I used them). ((I'm becoming aware of the infrequency of Vulnerabilities due to a player with the Dark Pact Warlock Daily that attacks a monster's vulnerability)).