Fire starter: a charged tool about as frequent as a tin opener that is primarily used not to create fires (because of the lack of firewood) but for getting released by plant monsters. It can also be used to burn grass off your current square.

Assassin vines should be able to grow or move into iron bar spaces. Possibly, being marked M1_SLITHY would suffice to allow this.

Add two types of vine to the plant class: a thief vine, which steals items from you, and a warrior vine, which is only found in bones files near the pile, and which starts with some weapons taken from the bones pile, which it uses to attack you with. (It would generate just after loading the rest of the bones level).

Thief vines, if adjacent to other thief vines, should pass stolen items away from the player, playing keep-away with them.