When making a deck in this game... do you know what each card does? Im on the fence about this.

Yes and no.
If you have "unlocked" the card by drawing it in your last game you get a good description.
If you include it for the first time you have no real idea what's going on.

Lets say Ive played some event cards... when it comes the time to build the event deck, those event cards that got played last game, the game will give you a description about them before putting them in the deck?

It gives you the first screen of dialog of the card, more or less. Not its possible outcomes.

The equipment cards all tell you what they do fully.

The encounter cards are the ones that don't. The thing is, a lot of the cards have many branching options; they're miniquests. They alter depending on the current villain (seemingly? or just change as you encounter them more? haven't gotten that fully), and have chances of success/failure in addition to you choosing your path through. That's a lot to fit on. But, I do agree that, any paths you've taken, should be displayable in the deck editor mode.

Example (roughly, from memory):
Treasure Chest
(dialog)
Choice:
Approach
Leave [never tried this option]

If approaching, do a success check (seems to be fixed 75% success rate).
If pass: Move to "B"
If fail: (text that you triggered a trap)
Choice:
Press on
Go back [never tried this option]

If press on:
Do a skill check to make it through the traps (seems to vary based on equipment)
If pass, move on to "B"
If fail, get some wounds and move on to "B"

"B": You're at the chest dialog
Choice:
Bash open
Leave [I've never chosen this one]

Bash open seems to have a 75% chance of giving you a gear or being empty.


I've seen certain quests have different options depending on what you have. For instance, one "goblin wizard" quest has an option missing if you're out of food when you encounter him.

Basically, you want an equal number of weapons, shields, armor, helms, and artifacts, if possible, so you're likely to get one of each and be fully equipped in time for the boss. If a level is going to be crawling with a certain type of enemy, pick weapons they're weak against. (eg. stack the deck with maces when going for a skulls face card).

As for events, prioritize cards that still have a token icon on the bottom, as beating them will unlock more cards. It's easier to unlock cards in story mode than infinite because you can stack the deck entirely with unbeaten cards.

If you don't mind a little grinding, you might want to spend time unlocking cards each boss before moving on to the next. The quests are much easier to beat in the early game due to weaker enemies, slower card shuffle, etc. Eventually you'll reach a point where you don't have room for any more until you beat a certain boss, so it's not like you'll run out of unlocking to do in the late game.