Wormwood Dryad

Landwalk evasion is usually fixed at printing: a creature forestwalks or swampwalks against whoever happens to control the matching land type, and against the wrong opponent the keyword does nothing. This green dryad sells that flexibility for life. Pay green and it forestwalks; pay black and it swampwalks; either way it costs you a point, and you can flip the mode turn to turn as the board demands. The self-damage clause is what keeps a 3/1 with toggleable unblockability honest. When the creature connects, the math still favors you (the opponent drops three, you drop one for the activation, a net two in your favor), but against the wrong basic-land spread you are spending mana and life to swing into a wall, and every activation chips at your own clock as a tax on aggression. The closest members of the landwalk family lock you into a single land type at the moment of printing; the wrinkle here is that both activations live on the same body, so a deck splashing black off a green base can find a profitable angle against a wider slice of opponents than any one keyword could promise. The damage is the leash, the dual mode is the leash's length, and the 3/1 frame settles the whole thing as a glass cannon rather than a threat you want to sit behind. It hits hard, dies to a stiff breeze, and asks you to pay in life for the privilege of being unblockable at all.