From Guild Wars 2 Wiki
Monthly PvP is an achievement category for PvP achievements earned by doing a set of tasks each month.
- Rewards: 5 Arcane Slivers, 5 PvP Glory Boosters, 5 PvP Salvage Kits, and 10 laurels. Laurels are only granted if the Monthly was not finished first--only the first completed monthly grants laurels.
- This achievement category was introduced in the November, 15th 2012 update.