Decks are built by subtraction
Most new players add cards and wonder why the deck feels weak. The fix is usually removal, not addition.
Your starting deck carries weak cards. Every one you delete makes the good cards show up sooner.
Shops and certain events offer removal. Treat those as high value, not as a nice extra.
Take or skip
Every card reward is a decision. Taking a card you will not use makes every future draw slightly worse.
The test is simple: name the plan this card serves. If you cannot, skip it.
A deck with one plan beats a deck with three half-built ones.
Upgrade or rest
Campfires force the same choice over and over. The answer depends on your health, not on habit.
Upgrade when you can survive the next few fights. A stronger card pays off for the rest of the run.
Rest when a bad draw would kill you. Health you never spend is wasted, but dying wastes everything.
Commit or hedge
By the middle of a run, your deck usually hints at a direction. Block engines, attack scaling, poison, or summons.
Committing means taking cards that push that direction even if a single stronger card exists elsewhere.
Hedging feels safe and plays badly. Pick the direction and feed it.
Read the boss before the act ends
Each act ends in a boss, and the boss decides which plan survives. Check what you are walking into.
A deck that ignores block will die to a boss that hits hard every turn. Adjust one or two cards early rather than rebuilding at the door.
Where to go next
The bosses page lists what each act can throw at you. The relics database shows what can reshape a plan mid-run.