Concerning playing a full campaign, I've read quite a bit regarding the topic of strategy with this game, and it appears that the overlord has at least a slight advantage over the heroes in this game. What I see in this game is the overlord's limits are based on which monsters are available (so pick the strongest of what is available), how much XP they have (buy the best cards as soon as possible), and which plot deck they use. In other words, pretty much everything is always available to the overlord, with some minor limits.

The heroes, however, have to choose their one character they will use, limiting their ability and feat for the entire campaign, their class, which again will limit what skills are available, and which members will be in the party, if playing with less than 4 heroes. They also can't simply buy whatever items they want, they are limited to 5 per quest.

I play with very competitive players, and I really do love it, but, do the heroes stand a chance if they don't pick optimal heroes? I have participated in 2 partial campaigns, one I was the overlord and the heroes picked an all orc team (Bogran the shadow, elder mok, and Mordrog) and they haven't won a game since First blood, all the way up to and including the intermission. The other campaign, I am a hero, that team is Leoric, Nanok, and Avric Albright and we haven't lost a single game up to and including the intermission.

I would like to start a new campaign soon, have a full party of 4 heroes, but the issue is how powerful the overlord will be. Currently we aren't using a plot deck, or rumor cards which appear to only skew the difficulty in favor of the overlord even more. Will the heroes stand a chance if they pick characters they like, or will they only survive with heroes that work together? There are some very cool miniatures and characters, that are sub-optimal due to their skills, and I don't mind playing as the overlord as a more casual overlord allowing the heroes a better chance at winning, but since the overlord is allowed to purchase nearly whatever they want, pick whichever plot they want, use whichever plot they want/don't want, do the heroes really have the freedom to pick any characters or only the best if they want to win? In our Orc campaign, I wasn't being overly aggressive, I was just steamrolling them. There were a couple of quests they just forfeited because they had no chance.

I'd love to hear thoughts on balance, are there things you have done to give the heroes a better chance to win if they pick fun over the best characters and classes, or if it's only my lack of experience in this game that is giving me the sense that the overlord has a slight advantage that is magnified greatly by sub-optimal hero selection. A thought I had was letting the heroes pick the plot deck the overlord would have access to during the game and potentially removing a few overlord skill trees, or limiting the overlord to only a couple of skill trees at the beginning that they would pick.

Edit: currently I have 3 HM packs, Base, Nerekhall, Lair of Wyrm, Trollfens, Labyrinth, and about 10 of the liuetenant packs (all base lieutenants and Nerekhall).

You have quite the collection started already! I wouldn't worry about top tier strategies though. Avoid googling the best setups and go for fun. Learning the strategies on your own is much more rewarding.

If you play really competitive, there are a few heroes/classes I would rather not pick:

Heroes:

Ashrian, Grisban, Dezra the Vile

Classes:

Spiritspeaker

Imo all the other heroes and classes are fine or at least viable. The strongest heroes and classes probably are the Liar of the Wyrm heroes and classes and the treasure hunter class, but I consider only the treasure hunter to be really problematic and bordering OP.

If the heroes perform really bad it's alsways possible to limit your monster selection to thematic fitting monsters or not play your OL cards.

You can also grant them more gold and/or maybe an extra shopping step if they are really unlucky with items or got a long losing streak and the quests start to feel one-sided and unwinnable.

I actually really like Dezra the Vile as a Battlemage:Knight.

She has enough fatigue to repeatedly make use of Guard and Advance, and her heroic lets her recharge her fatigue and health at the start of each activation (this is especially useful if she can use Advance to move next to monster groups that have already activated).