Giulainidh Sidhe (5e Creature)
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Large fey (sidhe), neutral
Innate Spellcasting. The sidhe's innate spellcasting ability is Charisma (spell save DC 11). It can innately cast the following spells, requiring no material components:
False Appearance. While the sidhe remains on all four, it is indistinguishable from an ordinary brown bear.
Little Bit Beastly. The sidhe is considered both a beast and a fey for any effect relating to its type.
Multiattack. The sidhe makes two attacks: one with its bite and one with its claw.
Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) slashing damage.
Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.
Guilainidh sidhes are shy and introverted, but also happen to assume a shape of a bear. This grants them unlimited freedom in the forest, since no one in the right mind would ever want to get in the way of a large, sentient, spell-casting bear. Because of this, guilainidh sidhes preferred to stay in the woods and mountains of the Material Plane, whereas their smaller-shaped cousins actively searched for humanoid civilization and society.
A forest inhabited by a guilainidh sidhe is protected by its fey denizen. A poacher, a lumberjack, or even an unfortunate adventurer who happened to need something from the forest without the local creatures' permission will soon face the nature's wrath, in a shape of a massive paw against their forehead or even worse, through their guts.