Aggro Forest is an usable deck in Rotation as well as in Unlimited. I sometimes play it on Master when playing Rotation, and it works for me (winrate with Aggro Forest: 3/5 matches). Aggro Forest decks are usally inexpensive
(approximatly 10000 vials), but very difficult to build.
-not on top of the food chain
-enemies will not predict you playing a deck like that
-very affordable (if you do not include Insect Lord)