Emerald Caller (Patreon)

Dagger, artifact (requires attunement)

This emerald dagger is a token of friendship from an old battle when a Horizon Walker Ranger called Thomas Oliver partnered with an Emerald Dragon to hunt down an ancient aberration threatening the material plane.

You have a +3 bonus to attack and damage rolls made with this magic weapon. The dagger has an intricate system that allows it to be used as a flute. The melody played by this magic weapon carries a promise that when needed, the Emerald Dragon will forever come to aid the holder of this emerald dagger against the perils of the Far Realm.

Emerald morphing. As an action, you can speak this dagger command word to summon a magic armor made of emerald and gold. The armor remains with you for 10 minutes or until you dismiss it. While wearing the Emerald Armor, your AC becomes 20, and you gain resistance to all nonmagical damage.

The item doesn't affect your AC if, without the armor, your AC is 20 or higher. Additionally, you can use an action to make yourself immune to nonmagical damage for 1 minute or until you are no longer wearing the armor. Once you activate the Emerald Armor, you can't do it again until you finish a short rest.

Song of aid. As a bonus action, you can play the legendary notes of the Emerald Caller to summon an Ancient Emerald Dragon through a Planar Gate. The Dragon is friendly towards you and your allies and will aid you at the best of its power against any external threat invading the material plane. After the battle, the Dragon will return to his Lair. The dagger is not to be used in vain. If the Dragon believes you called him for an unworthy mission, he can revoke the dagger's powers, turning it into a mundane item.