I've been advertising my League of Legends convention on reddit for a few weeks using the League related subreddits (leagueoflegends, leagueofmemes, loleventvods, leagueoflegendsmeta)

The result? The CPM is low and the CPC has hovered between $0.09 and $0.20, but so far reddit ads have accounted for 0 of our sales (out of a few hundred tickets so far). Location targeting would be amazing, but you can't target a subreddit and a location at the same time.

Our ads will steadily change to increase the sense of urgency as the date approaches (X days left, Y tickets left), it will be interesting to see how it plays out.