Batman: Return to Arkham - Arkham City

Campaigns are strings of 3 maps, a mix of Combat and Predator maps, for 9 medals in each campaign, and a total of 12 standard campaigns. The extra content campaigns do not count for this trophy.

The most challenging part about campaigns is that all 9 medals must be attained in a single run. You get to retry maps in a campaign up to 3 times, so if you’re feeling like your run was not up to snuff, you can retry for a better score. Note that retrying the first map doesn’t use a retry, it’s effectively the same as starting the campaign again from the Riddler’s Revenge menu, so for all intents and purposes, you have 3 retries to use for the latter 2 maps in a campaign.

Each campaign map also has modifiers make the map harder. You have to use all three in a campaign, which means if you'll be forced to use the modifiers in the final map of the campaign if you haven't used them. We would argue the best of these modifiers is the Free Medal, which is exactly what it sounds like. Pick this when you get the opportunity to on a second or third map in a campaign. We would not recommend using it on the first map, as the first map doesn’t use retries anyway and you can just keep trying to get the score you need.

PowerPyx has developed an excellent challenge maps guide, which can be seen here. That page features a list of tips and recommended challenge modifiers.