Bones of the Land

You plant a bone charm into the earth and perform a necromantic ritual. A fully sized, gnarled tree made entirely of unidentifiable bone sprouts from the earth. The tree releases an aura of necrotic energy, and begins to shower the surroundings with shards of bone. Hostile creatures within range must make a dexterity saving throw and beat a 15, on a failure they take 5D6 piercing damage, and take an additional 5d6 necrotic damage at the start of each of their turns. On a success, the target takes half of both damage. Additionally, friendly targets within range become bolstered by the necrotic energy. They gain a number of D6 worth of temporary hit points equal to your spellcasting modifier, and have resistance to necrotic damage. When the spell ends, the effects cease, while the tree remains inert. You may spend another 5th level spell slot to reactivate the tree. Otherwise it will remain unless something destroys it.