Bushwhack

The choice happens at cast time, and that timing does the heavy lifting: two of green's oldest reflexes, land-fixing and creature combat, sharing one slot where a deck used to run both separately. On an empty early board, the first mode guarantees a land drop of the right color, pulling a basic straight to hand as a curve-smoother that never accelerates you (basics only, and only to hand, so it fixes without ramping). Later, once a fat green body has landed, the second mode reads as a one-mana Prey Upon, throwing your creature at an opposing one and hoping the power totals break your way. Neither half is best-in-class; that is the toll for the flexibility. The fight is a mutual-damage exchange that can bury your own attacker if you misjudge the numbers, so it wants oversized creatures behind it rather than the clean point-and-shoot of dedicated removal. What you buy is compression: one card occupying a spot in the green curve where you cannot yet tell whether the turn will ask for a land or a fight. It will not win by itself, but it almost never rots in hand, and for the awkward opening turns of a green deck that is a precise, well-calibrated form of insurance.