Act 8: Sabre of the Wild Blue Phlox

You reach within the moonblade and draw upon its power, thunderously shifting between the Material and Ethereal Planes like a leaf in a storm. As a free action on the turn you cast this spell, you can make one melee weapon attack with the moonblade used as the spell's material component. On a hit, the attack deals an additional 8d4 thunder damage. Additionally, you gain the following benefits:

• Passive: Petal Dance. When you cast this spell and at the start of each of your turns, you choose whether to occupy the Material Plane or the Border Ethereal (as if you had cast the etherealness spell). Whichever you choose, you remain on the chosen plane until the beginning of your next turn. When the spell ends, you return to the Material Plane if you are in the Border Ethereal.
• Passive: Rapid Propagation. Your movement speed is doubled, and you can move through hostile creatures' spaces and stop there. A space occupied by a hostile creature is treated as difficult terrain unless you are in the Border Ethereal. If you occupy the same spot as a creature when you end your turn on the Material Plane, you are immediately shunted to the nearest unoccupied space that you can occupy and take force damage equal to twice the number of feet you are moved.
• Passive: Scattering Blossoms. The first time you enter a creature's space on a turn, that creature must make a Constitution saving throw. On a failed save, they take thunder damage equal to 8 + your Spellcasting ability modifier and are pushed up to 10 feet in a direction of your choice. If you are on the Ethereal Plane, they instead take twice as much damage, are pushed twice as far, and fall prone. On a successful save, they take half as much damage and are not pushed or knocked prone.
• Passive: Root Wedging. Your melee weapon attacks against objects and structures hit automatically and deal double damage.
• Bonus Action: Shatterspall. While you are in the Border Ethereal and occupy the same space as an object or structure on the Material Plane, you can target that object or structure as a bonus action. The target takes 8d6 thunder damage. If this damage reduces the target's HP to 0, each creature within 30 feet of the target must succeed on a Dexterity saving throw or take 3d8 damage. The damage's type depends on the material of the destroyed object or structure (for example, stone might deal bludgeoning damage, while glass might deal slashing damage)
• Reaction: Sudden Inflorescence. When a hostile creature you can see within 30 feet of you casts a spell, you can roll a d8. If the number you roll is higher than the spell's level, it fails and the target is deafened until the start of its next turn. If you are in the Border Ethereal, you may re-roll this die once and must use the new result.

Denouement: Repudiation of Hanali. When this spell ends, you may choose any number of creatures within 30 feet. Each target must make a Constitution saving throw. On a failed save, a target is thrown 1d8 x 10 feet directly away from you. A target stops moving when it collides with a surface or a solid object, taking 1d6 bludgeoning damage for every 10 feet it traveled. The damage dealt in this way is nonmagical.