After the quest compendium, the translation of the RtL, the news about the core game being selling again, and the card teaser we can consider that the time is coming. So what would you like it to feature? We could inspire the game designers to add something we actually are asking for if they read this. Who knows?
These are some things I would apreciate:
Monsters: Balance the groups! When the RtL was released we had 7 kinds of humanoids, 7 kind of beasts and 6 kinds of eldritches. I don't own the ToI, but my guess is the current monsters feature: 7 humanoids, 10 beasts and 8 eldritches. I would like the expansion to balance this to 10 each. We desperatly need a tier 2 humanoid and a tier 3 eldritch. Completing the monsters familys would be a nice idea too. How about an upgrade from the kobold (an imp for example) or a downgrade from the demon (a djinni)?
Overlord cards: The basic deck grows with every expansion (that's not bad) but the proportions favor more and more the spawns. I would like to see more events, traps and power cards. Indeed, I would add 12 cards to the deck: 5 events, 2 spawns, 3 traps and 2 powers. One of the power cards would make the deck worth one extra conquest toquen (or maybe two if it is expensive enought). I would like to see traps that have to do with potions (like poisoning a potion, giving it a side effect or making it useless).
Feats and treachery cards: Yea, add some more. 8 more feats per type would be good, while the treachery cards should be enought with 3 or 4 each. I'm still looking foreward to see the complete list of capital sins as power cards. Before the ToI we had Glutony, Warth, Envy, Pride and Greed. I'm still waiting to see Sloth (can't remember if that card actually exists already) and Lust (how to represent that?).
New plots, avatars and lieutenants: An excuse to make 3 more avatars is to add a way to use some of their stats in vanilla descent. For example, instead of starting with a fixed number of treachery in each color, start with a combination that suits the avatar (give more spawns and less events to the titan for example). There should be something for the heroes to balance this isue.
Heroes: if we have more avatars, then two more heroes would be enough. I would like them to be strange ones (like Karnon and Arvel). For example, 3 black dice in everything but no skills. The character spetial hability would allow him/her for an extra attack with a diffrent weapon every time.
More quests and if possible the addition of a green runed door. Instead of adding a lot of levels to the RtL, I would give options for the existing ones to feature the new monsters. The new Lieutenants would force encounters with the new monsters too.
What else would you like?