Hi Lex - yeah from the Warmaster Trial Armies 2009. Is there another source?
There as always a lot of hubhub on the subject of having armyselectors for an "army" that at its best would be like a allied division for a Bretonian army, all on account of the limited numbers of woodelves in GW lore.
There are at least 2 other (earlier) lists. The list that ended up in the Trial Armies is a "normalized" version of one of those, in the original list Waywatchers where one-shot artillery, hence the ignore armour, instead of a generic +1 to the AST of the target (like handgunners)