Acorn of the Tree Guardian

You may designate a command word that triggers this item's effect when treated with at least a single drop of water. This acorn then bursts apart with a stem and roots that quickly expand and grow into the form of a treant.

As an action, you may awaken the acorn and throw it to a space within 30ft of you where the creature begins to take form. This space must have enough room for a creature of size Huge.

This creature is friendly to you and your companions, and it rolls its own initiative in combat. You can use a bonus action to command how the creature moves and what action it takes on its next turn, or to give it general orders, such as to attack your enemies. In the absence of such orders, the creature defends itself from hostile creatures but otherwise takes no actions.

Once summoned, the creature remains for up to 10 minutes or until it dies, at which point it withers away and drops another acorn that can be used after the next dawn. If the creature dies to fire damage, it drops a seed that crumbles into ash and is permanently destroyed.

Notes: Summoning