Tree blights that are hiding and motionless should actually use the game’s “appear as furniture” system to appear fully as dead trees, so that even if you farlook them they just show up as “dead tree”. Currently they have the same ASCII glyph but appear as “tree blight” in farlook, allowing you to trivially scan the map and confirm any suspicious-looking dead trees to be blights or not. This would also enable the tree blight tile to be distinct from the dead tree tile.

Scroll of nature, which creates grass, trees, and shallow water in a radius around the player (larger if the scroll is blessed). If cursed, it summons blights. Druids should start with one or two of these so they will still be able to employ grass tactically even if they don’t start with the spell of create grass.

Gulthias trees should have an attack that starts a timer where you gradually turn into a blight, which ends the game if you succumb to it (without life saving, at least) since you have been converted, similar to how turning to slime works. Also similar to sliming, if you become a blight, you should be one in any bones file that gets created.