From the Publisher:
Critical Hits are a closer look at situations that are frequently ignored in the course of a campaign. It is all too easy for the DM and players to focus only on the main storyline. Periods spent on the road or resting are populated with random wandering monsters or a four-day journey is simply collapsed into "OK. You get there?"
Critical Hits are there to fill these spaces between the story elements with unusual and interesting, sometimes comical but always memorable encounters. The DM can keep the players guessing over which encounters are part of the main story and which is a Critical Hits filler or red herring. When the players think that every action, no matter how insignificant, may impact upon their characters? chances of survival, they start to immerse themselves in the campaign setting. Critical Hits present PCs with a range of situations that distract them from their quests and breathe life into your campaign.