Scales the color of emeralds armor this ferocious dragon. A single sharp horn protrudes from the end of its toothy snout.
5e SRD
A proud, ancient race of gigantic, carnivorous, winged reptiles. There are many subspecies of dragon, many of which are distinguished by the colour of their scales. All dragons are egg-layers and hoard treasure in their lairs, far from areas of human civilisation.
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Foul-tempered dragons that prefer caverns or ruins in or near forests
Particularly renowned for their foul temper, which is said to be even more venomous than their breath, green dragons prefer to live in caverns or ruins in or near forests.
Green dragons sometimes (45%) speak, rarely (20%) cast magic, and will sometimes (40%) be found asleep. If the dragon is asleep, there is a 1 in 6 chance that it will awaken in the presence of adventurers. Dragons also sometimes feign sleep.
If a green dragon can cast spells, it will do so as a magic user equal to its age category. Thus a green dragon with 6 hit points per die can cast spells as if it were a 6th level magic user. Owing to the magical nature of the creature, it does not require somatic or material components to its spells—it need only speak the incantation.
OSRIC