Being one of the starter evolutions, this is likely a card that many players had on hand at one point or another and may not have realized the value it would one day hold
It makes use of several other key cards like Argothian Opportunist that just miss the top 3 commons, as Green is fairly deep here with good commons
Investigate isnt an activated or triggered ability on its own its a keyword action
While the first ability suggests youd limit this card for more aggressive decks, you can even neutralize a blocker for the benefit of another opponent in a multiplayer format like Commander
They might have been already printed cards, that were later used in the non-1st edition Shadowless print run, which already had these E ITION printing indication applied to them in an earlier step of the printing process
Beyond those three, its anyones guess, but Ive been through the list of available mechanics and keywords to pick out what seems the most likely: Battlecry A Go Wide strategy is likely given the huge armies and battles in the series, and battlecry is a way to help break stalemates