In this guide, I'm going to give my thoughts on my own party setup (Seoni/Lem/Lini/Valeros), how I generally played their turns, what cards I chose for their decks, and what choices I made when upgrading their skill/power/card feats. As an example of what happens when things go well: I got a 90 on my final combat roll against the final boss in normal difficulty.

As a disclaimer:

• This is probably not the best (most optimal) way to play but it worked well enough for me in normal difficulty.
  
• The first two adventures were pretty tough for me as I was learning the game and you don't have the raw stats/cards needed to make runs consistent. However, as I got better cards and more feats I was more consistently successful. I was able to get most important checks to 90%+ if I was prepared for it.
  
• I tried to explain the reason behind most of my decisions but know that some of these (especially in feat choice) are more personal preference than the factually right/best choice.

I made this guide because I read a review that said someone liked the game but got stuck on a level and gave up on the game. I hope this helps people get through the difficult stuff.

Introduction:

The difficulty of the game varies based on how many party members you take and who you take. If you take less people you'll have less locations to clear to reach the boss but you'll miss out on buffs your allies can apply to each other (especially blessings) and you won't have any character to supplement your weaknesses. The blessing deck (game timer) will probably be less of a concern than running out of cards in your deck. If you take more people you have more locations to clear but the same game timer (30-turn blessing deck). This means you need to clear things efficiently and spend allies/blessings/powers to close locations as fast as possible.

I chose 4 because I wanted to play as big of a party as I could (but I had a miserable time trying to run with 6 early on) and the game itself recommended 3-4 in a party.

I tried out every character I had access to but settled on Seoni, Lem, Lini, and Valeros. I wanted a party that did well in general use, buffed allies, and relied more on revealing/recharging than burying/discarding.

Seoni:

Seoni is an incredibly consistent spellcaster/battlemage because you automatically recharge all spells cast. She burns through your own deck quickly (when you discard allies/blessings for exploring locations or for her fire attack) but can similarly clear location decks just as quickly.

Other thoughts:

• The Wand of Enervation loot card that you are guaranteed to get halfway through the campaign is an incredible card (arcane item, bury/recharge to decrease combat difficulty by 1d4+4) that seems made for her. Decreasing combat difficulty by 5-8 is amazing for increasing your odds of success.
  
• She can get a feat to make all her blessings a d12 (if you load her with all spell/Pharasma blessings), which pretty much guarantees any spell combat checks and makes her blessings better for general use.

Lem:

Lem is an incredible support because of his ability to recharge a card to add a die to any allied skill check (while in the same location). He's on the weaker side if he has to encounter stuff himself (unless you have a combat spell or until you get the upgrade to inspire yourself). He has divine, so he can cure himself/others. While he isn't great at recharging spells, his other ability to swap out a spell for one in the discard pile let me cure multiple times anyway (if you intentionally fail the cure recharge check you can cast it again next turn by swapping a spell for it). And as the cherry on top, he can even get a feat that makes his blessings a d12 (assuming you load him with all the Wisdom/Shelyn Blessings, which is so useful for the common wisdom checks).

Lini:

Lini is incredibly consistent against almost all checks because of her ability to reveal an animal card to add a die to every skill check. She has divine, so she can cure (plus the animal card bonus means recharging isn't a problem).

Valeros:

Valeros is slower than the others in burning through location decks (because he doesn't have many blessing/ally slots to keep exploring, at least until you upgrade his deck slots) but at least he's consistently good at combat. The problem with weapon cards is that if you draw too many you can't recharge them without getting into combat. I didn't want to discard too many of them (at least when you have too many armor cards you can usually recharge them at the end of the turn) so he never really was able to get through much of the location deck each turn (by drawing allies/blessings and using those to explore). I took him for his passive allied combat buff and to round out the party (though I found out later there aren't many strength checks except for the non-essential collection of weapon cards).

Thoughts on other party members:

Kyra seemed pretty good but I had three casters (two divine) already and wanted to balance it out. Also, most of my characters recharged instead of discarded so it wasn't as necessary to have an every-turn healer. Harsk seemed similar to Valeros but I wanted someone with high Strength to balance out the party. The other characters seemed alright but I didn't like that they discarded/buried cards (the longer the game goes, the worse off you are) or had too strict conditions for my liking (like you must be alone in the location). They are great in more niche conditions but otherwise feel worse most of the time.

Introduction:

Skills: In general, I prioritized combat skills (spellcasting/melee/ranged) then Wisdom/Dexterity because they seemed to be the most common check.
Powers: In general, I prioritized all-purpose buffs/hand size then utility. I avoided buffs to acquiring stuff.
Cards: In general, I prioritized blessings (for the buff/exploration), then allies (for the exploration), then spells/items, then armor/weapons (with the armor proficiency power you can recharge extra armor but you can't do the same with weapons. I only wanted 1-2 armor and weapon cards in-hand at a time).

Seoni:

Skills: I prioritized Charisma for spellcasting then Wisdom/Dexterity for checks.
Powers:

• Sorcerer: Hand Size, then Magic in the Blood, then a point into Arcane Blast.
  
• Celestial Sorcerer: Lady of Graves' Favor, Acid Blast, Fortune's Herald

Cards: I prioritized blessings/spells then items. I would've liked the ally slot but there ended up being too many good items to pass on the item slot.

Lem:

Skills: I prioritized Charisma for spellcasting then Wisdom/Dexterity for checks.
Powers:

• Bard: Bardic Performance then Weapon Proficiency (Light Armor Proficiency might have been better).
  
• Virtuoso: The Rose's Favor, Solo Performance, everything else in Bardic Performance. It might be worth taking a point off of Bardic Performance to put into Bardic Lore because I found his recharge checks late game were at 80%.

Cards: I prioritized blessings/allies/spells, then items, then armor/weapons.

Lini:

Skills: I prioritized Wisdom for spellcasting then Strength for Beast Form combat.
Powers:

• Druid: Animal Trick then Light Armor Proficiency (maybe Weapon Proficiency is fine? I never added armor/weapon slots to my deck, though).
  
• Wild Warden: Everything into Animal Trick.

Cards: I prioritized blessings/allies/spells, then items.

Valeros:

Skills: I prioritized Strength for combat checks then Dexterity for Dex checks or for if I acquired a random ranged weapon.
Powers:

• Fighter: Hand Size/Teamwork. There aren't enough feats to choose anything else.
  
• Weapon Master: Everything into Teamwork. I chose Weapon Master for the extra teamwork but looking back I feel like Guardian might have been better for the Shield Another power.

Cards: I prioritized blessings, then allies, then items, then armor/weapons.

General Thoughts:

Spells: I avoided evasion spells (like Sleep/Invisbility/Sanctuary - because I could just beat the checks most of the time) and put a majority of my spell slots as damage spells for combat encounters. I kept a minority of spells for utility (like Augury, Scrying, and Aid). Other utility spells seemed okay but too niche for limited spell slots (like Agility/Strength/Eloquence/Mending/Stride). I didn't like Detect Evil/Magic because there's a good chance nothing happens and spell slots are limited. Mirror Image and Arcane Armor are nice but if things are going well you can often just win the combat check to avoid damage (or use armor/items or just take it for unavoidable damage).
Weapons/Armor: I preferred the most generically strong equipment (reduce any damage by 2) over specific ones (like reduce ranged damage by 3). I didn't use shields because Valeros used 2-handed weapons (but either way, ranged damage is pretty uncommon).
Items:

• There is a large variety of items but a decent amount of them require the arcane skill to recharge instead of bury.
  
• Wand of Enervation is probably the best item out there when you're facing a villain/henchman.
  
• For damage-mitigation, Ring of Protection and Sihedron Medallions (or its lesser equivalent Amulet of Life) are good. Wand of Shield and Bracers of Protection are less useful because they're restricted to combat damage (which usually means losing a combat encounter).
  
• Wand of Scorching Ray and Wand of Force Missile are alright if you want more arcane combat spells.
  
• I used Staff of Minor Healing to fill out item slots to help keep decks healthy.
  
• I shied away from 'add 1 to a specific check' items because they are pretty niche and I felt there were more useful items.
  
• Masterwork Tools was my favorite anti-barrier card.
  
• I used Medusa Mask with Lem until I got Yap the Pixie.

Allies: Lini is best with Animal allies for her power. Otherwise, I took allies with abilities that buffed what they did often like combat or general checks (but I almost always used them for the ability to discard to explore). If they didn't let you discard to explore I probably wouldn't take them (unless the ability was very powerful and not niche so you wouldn't hold onto it forever and not be able to use it).
Blessings: Some characters (with the right power feat) make blessings use d12 (instead of the regular die) so it's easy to choose the blessings they hold. Otherwise, non-combat Dexterity/Wisdom is fine for checks or utility blessings (like Blessing of Gozreh to close locations) seem nice filler.

The decks I had before the final scenario (Some cards are filler or non-optimal):

Seoni:
Spells: Disintegrate, Poison Blast, Lightning Bolt, Fire Sneeze, Haste, Scrying
Items: Masterwork Tools, Sihedron Medallion, Staff of Minor Healing, Wand of Enervation, Amulet of Life
Allies: Black Arrow Ranger, Poog of Zarongel, Sage, Troubador
Blessings: 6x Blessing of Pharasma, Blessing of Calistria

Lem:
Weapons: Venomous Heavy Crossbow +2 (it was Allying Dart +1 before I had Weapon Proficiency)
Spells: Aid, Charm Person, 2x Cure, Frost Ray, Holy Light
Items: Robe of Runes, Sihedron Medallion, Wand of Treasure Finding, Staff of Minor Healing
Allies: Ayruzi, Black Arrow Ranger, Mountaineer, Pyromaniac Mage, Yap the Pixie
Blessings: 6x Blessing of Shelyn

Lini:
Spells: Mass Cure, Major Cure, Swipe, Inflict, Holy Light, Aid, Scrying, Invoke
Items: Sihedron Medallion, Emerald Codex, Headband of Inspired Wisdom
Allies: 2x Monkey, Cat, Bear, Saber-Toothed Tiger, Toad
Blessings: Blessing of Nethys, Blessing of Calistria, Blessing of Gozreh, Blessing of Iomedae, Blessing of Lamashtu

Valeros:
Weapons: Mokmuian's Club, Flaming Ranseur +3, Impaler of Thorns, Flaming Icy Axe +1, Fanged Falchion, Greatclub +3
Armor: Greater Bolstering Armor, 2x Invincible Breastplate, Goblin Plate +1
Items: Masterwork Tools, Revelation Quill, Ring of Protection, Thieves' Tools
Allies: Black Arrow Ranger, Sheriff Hemlock, Jakardros Sovark, Standard Bearer
Blessings: 4x Blessing of Gorum

General:

• Strengths: You have 3 spellcasters for arcane/divine checks, Lini is probably the best for all-around checks. You have a lot of ways to buff checks for allies.
  
• Weaknesses: Wisdom is low (except for Lini), Dexterity and Con are mediocre (d8 for most). Unless the difficulty is low enough for Bardic Performance (or the punishment on failure is too high), Wisdom and Constitution checks are usually better failed than spending blessings to pass. For Dexterity checks, you can often get away with having Masterwork Tools or other lesser items against barriers (I was lucky enough to find two Masterwork Tools).
  
• Your goal most of the time is to close most/all locations and then finish off the villain. There's no reason to temporarily close locations unless you're going for the final blow.
  
• If you find yourself running out of cards in the blessing deck (30 turns ran out), you need to keep your buffs for the important checks (give up on all card acquisition), use certain items/spells (Invoke is a great late-game spell) or try a smaller party. This gets easier the later in the campaign you go (because you get better cards and more feats).
  
• If you find yourself running out of cards in your deck you need to avoid using cards/powers that discard/bury/banish, spend turns using the Cure spell (and the Staff of Minor Healing), carry more defensive spells/items to avoid damage, or try using more party members.
  
• Augury/Scrying/Revelation Quill is pretty useful. I most often used them to put generic enemies at the bottom of the location deck to avoid unnecessary damage and unnecessary waste of turns (or to put henchmen/villains on top to close the location faster).
  
• By the end of the campaign I was able to consistently close locations by defeating henchmen/villains. Remember that if you defeat a villain you don't need to pass the 'closing location' check!
  
• There are rolls that are not worth it to pass. Sometimes it's better to just take the damage (and hopefully you have some armor/item card to mitigate the damage).
  
• Ending your turn with no cards is fine because you draw to a full hand at the end. So feel free to use your stuff to boost your success rate (unless you're saving it for an ally's turn/a future encounter). Of course, you must be careful when you're low on cards in your deck and make sure to use Cure often (especially for Seoni).
  
• Know that you don't always need to wait until a character's turn to cast spells (like cure). Just temporarily switch to their character overview by clicking their circle-icon.
  
• If you have 0 cards at the start of your turn, it may (or may not, if you're unlucky) be worth it to explore anyways because it might not be so bad. Best case you get rid of a card in the location deck, if you lose a battle you don't have any cards to discard, but worst case you trigger some effect that damages all allies or discards from your deck/the blessing deck.
  
• I paired Seoni with Valeros and Lem with Lini and it worked well enough for most situations. I switched things up as necessary (different locations have different conditions that can influence your play).

Seoni:

A generically good hand for me would be two attack spells and a bunch of blessings & allies (and maybe a utility item). Explore, fail/succeed card acquisition checks, win combat checks. Spend allies & blessings to keep exploring (though you may want to save some if all of your allies ran out of buffs). If you run out of attack spells you can use the Arcane Blast power (though try to avoid it because it discards). Once you run out of cards (0-2 left) or have no way to keep exploring, end turn.

Lem:

I usually used Lem's cards for Bardic Performance so when his turn came around he had only a few (or no cards) in his hand. If he has no cards you might want to pass the turn doing nothing (or take your chances and hope you don't draw an card that damages other members in your party). With Medusa's Mask/Yap the Pixie I was more free to explore a location without being ready for the consequences.

Lini:

It's important to keep an animal card in hand at all times. So if you're hit with unavoidable damage (or an unlucky combat check) try to save the animal card for last. Similar turn as Seoni (preferring attack spells over discarding for Beast Form) but you'll probably acquire more cards.

Valeros:

I don't think I played Valeros as aggressively as I should have but I wanted to play things more safely. I usually only got 1-2 explorations out of him per turn because his hand was often filled with weapons and I didn't want to needlessly discard extra weapons for the hope of drawing other cards (and only later did he get a more balanced deck with blessings and allies). Since you have so many weapons, feel free to discard weapons for the extra die (weapons automatically recharge with him). He's pretty good at combat but only mediocre at other checks.

Concerning the main (non-DLC) campaign:

Character have an obvious skill to raise (that directly affects their combat skill) but picking a second skill to boost (and what blessings to take) was difficult for me. I could definitely be wrong about the following, just guessing based on the cards I've noticed while I played:

• All skills are for used for acquiring certain cards (STR for melee weapons, DEX for ranged, CON for armor, INT/WIS for spells and magic items, mostly CHA/WIS for allies). But it feels less important because there are catch-all buffs (at least if you have Lem and Lini) to acquire stuff. It's not as relevant to winning the scenario as the checks against enemies and barriers (that have penalties).
  
• Dexterity seems like a decent catch-all. It's used in many barrier checks and some monster checks. Wisdom also seems to be a pretty common check. They're both common for 'if you fail, bad stuff happens' (non-acquisition checks). As a side benefit, dexterity is used in ranged if you randomly acquire a ranged weapon.
  
• Charisma, Intelligence and Strength feel less used. At least Strength is used for melee combat if for some reason you're fighting without any cards or randomly acquire a melee weapon.
  
• Constitution feels barely used except for the rare 'pass or take 1d4 damage' or something like that.

For elements (magic spell types):

• Fire: Most common on cards and the most common weakness. There are several cards that can add the fire trait to an attack.
  
• Poison: Often resisted.
  
• Mental: Often resisted, but mental spells seem more for evading battles than damage.
  
• Cold: Sometimes resisted.
  
• Acid: Rarely resisted.
  
• Electric: Rarely resisted.
  
• Force: Barely ever mentioned.
  
• Some things require the divine/arcane/magic traits.