Frozen Fields is a 3v3 map released for StarCraft as part of the 2014 Season 2 ladder map pool for Heart of the Swarm
Official Map Description
There are two paths into your main fortress, so guard both carefully. In the later stages of the game, the key to victory is defending the wide ramps leading to your expansions.
References
Blizzard Entertainment. StarCraft II: Wings of Liberty. (Activision Blizzard). Map: Frozen Fields (in English). 2011