Green dragons can be assigned as a slayer task at level 52 combat by Krystilia after partial completion of Dragon Slayer I. As Krystilia is the only Slayer master to assign green dragons, they must be fought in the Wilderness, and other variants outside the Wilderness do not count. They attack with melee and dragonfire, thus some protection against it should be considered. Due to their large size, they are usually able to be safespotted with ranged or halberd-like weapons. As dragons, they are also weak to dragonbane weapons.
A majority of dragons are above the level 20 line, thus a level 30 teleport such as an amulet of glory or royal seed pod is recommended for escaping player killers. A small cluster of three dragons can be found below level 20 Wilderness just west of the Dark Warriors' Fortress, making it ideal for killing with good attention, as the use of a teleport tab is enough to escape any hostile players. The dragons near the Lava Maze are above level 30 Wilderness, and thus it is not recommended to kill them there.
Dragonfire
Monster Variants
Location Comparison