What it does is you can craft and place artifacts on your troops. Academy has good summoning magic, and a thing called artificial. The dungeon has a low number- powerful troops thing. What it does you can choose one creature and you mostly do more critical damage too it, at first having to kill 2 whole populations of that creature. Sylvans, in my opinion, have powerful archers. Percent depends on ability level (from 20% to 50%). What it does it raises fallen troops in battle. Inferno strength is that they can have hordes of troops by using their copy-paste ability called Gating.
Haven is balanced troops, light magic (Good buffs) and powerful Angels (Last troops of haven).
It is good to know what is your faction strength. It has all 8 factions, but campaigning is different from an original. I would recommend buy HOMM V Tribes of the east directly if you are not interested in campaigning. This game originally has 6 factions (haven, inferno, necropolis, sylvan, dungeon, academy), buying that called DLC (they are not DLC) you get +2 factions (fortress and stronghold).
