Quests in Diablo II are a fun part of the game, and some must be completed in each act to advance to the next Act or difficulty level. Diablo II has Four Acts with six quests in the first three acts, (and one secret bonus quest in Act One) and three in the final act. The Expansion adds a fifth act with six more quests, but doesn't change how any of the quests in the first four acts work, other than adding a little bit to the last quest in Act Four.