In your opinion, which faction is the strongest in Heroes 5? Let's discuss the advantages and disadvantages of each faction.

It's most difficult for the Dungeon to play against the Academy (mirror match rules).

The mirror doesn't seem to affect Chaos magic spells that are tied to an area, rather than a specific unit. And a good half of them are like that! (stone spikes, fireball, ring of cold, meteor shower, armageddon) Use them against mages!