Bungie has said the Halo 3 Legendary Map Pack will go Live on 15th April.
It will cost 800 Points (GBP 6.80 / EUR 9.60) and contain three maps: Ghost Town, Avalanche, and an unannounced level.
Avalanche is the latest to be detailed, and is a "reimagination" of the original Halo map Sidewinder.
It still has the same U-shape of old, but has lost its ladders and changed the focus from deep interior portions in favour of more snowy fun outside in vehicles, which should all look suitably wintery.
The Bungie team thinks CTF works the best on it, and you can read the rest of their comments on the official website.
Remember, this special Easter weekend hopper sees the return of Team SWAT from Halo 2. That means no shields and no radar, but extra health. This will run from tomorrow until Sunday and treat you to double experience.