The Heroic Map Pack includes the maps Rat's Nest, Standoff, and Foundry. It was originally released on December 11 of last year, at a price of 800 Microsoft Points ($10).
"Remember, as of the April playlist update, the Free Heroic Maps will be required in Ranked Big Team, Social Big Team, Team Slayer and Rocket Race playlists," wrote Bungie's Luke Smith.
"We're requiring these maps in the following playlists to give players more options with the map rotations and by including a high population playlist like Team Slayer, we hope that the maps will permeate through the Community, resulting in more games played on these maps in Matchmaking."
The upcoming Legendary Map Pack is still on target for an April 15 release. Much like the Heroic Map Pack, it will initially sell for 800 Microsoft Points ($10), though Bungie claims it is unaware if or when the Legendary pack may become free.