All avatars of the Inner Court deities have the following abilities, usable at will (unless specified differently), in addition to those listed in their specific entries:
charm person, detect charm, detect magic, detect invisibility, ESP faerie fire, forget, goodberry (6/day), know alignment, plant growth, speak with animals, obscurement.
All of them can pass without trace and can move silently and hide in undergrowth (as shadows) at 95 % rating.
These magical abilities only operate while the avatar is in a sylvan setting and for up to 10 turns after leaving that setting (which may be any woodland, not just a "deep sylvan" environment).
All sylvan deity avatars are immune to poison, disease, caused wounds, death magic, polymorph attacks, and non-magical weapons; these immunities are not affected by the setting in which the avatar is encountered.
The avatars share certain other characteristics.
Most have very low Armor Class, due to their small size, speed, and Dexterity, and their highly magical nature. Their AC rating is worsened by + 4 if they are encountered outside a sylvan environment.
They have high magic resistance values, again due to their magical nature; but these are halved if the avatars set foot outside the sylvan realms.
Their weapons and armor differ from those of the avatars of larger beings. Specifically, their weapons do less base damage than others of the same type due to their small size (so, a faerie dagger does a base 1d3 points of damage to a medium-size opponent, for example). Their armor, for the most part, is gossamer armor spun from enchanted spider silk mingled with moonbeams. It is treated as + 5 magical armor for the purposes of determining saving throws and the like.
Finally, no faerie creature or natural woodland animal (nor sentient nonevil plants such as treants) will attack an avatar of a sylvan deity even if magically controlled.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.