Left-click a monster or choose Attack from its action menu. Friends can attack the same monster, so you can tackle stronger creatures together. A monster’s listed attack is a range before your defences. Armour and shields combine with diminishing returns against creature attacks: stronger equipment still protects better, but heavy blows can hurt through it. Blocking improves shields; food and healing remain important against strong creatures.
Bows require equipped arrows. Arrow tiers have different durability; both hits and misses use wear. A quiet warning appears when your equipped arrows have ten shots or fewer left, accounting for their quality and wear. Spare arrows in your bag must be equipped before they count. Keep a backup melee weapon, food and mana. Running out of arrows does not prevent spell casting. Staffs improve damage spells, but ordinary staff attacks are melee attacks.