Crafted by the legendary Hephæstus as a gift for Zeus, the Throne of Olympus is a magical and ornamental chair. The frame is forged from solid gold, polished to an illustrious shine, and decorated with ornate reliefs of flowers, vines, and cherubs. The seat is padded with the finest goose-feather down, and stitched with cashmere fabric and elaborate embroidery. The Throne is completely indestructible and never tarnishes.

The most unusual feature of this chair, however, is a rocker-switch located under the right armrest. By pressing it forwards, the Throne steadily increases in size, whereas pressing it backward causes it to steadily decrease in size. You can use your Action to hold the switch in either position, and so long as you are not incapacitated, knocked unconscious, or otherwise forcibly removed from the switch, the Throne either increases or decreases by one size category at the start of your next turn (to a minimum of Tiny or a maximum of Gargantuan). While changing size, the Thone emits a soft humming sound and gently vibrates.

The Throne grants half-cover to anything next to it which is smaller than its current size, but also counts as difficult terrain for movement purposes.

If the Throne expands into a space occupied by a creature that is neither prone nor on top of it, that creature must make a DC 12 Dexterity saving throw. On a failed save, the creature takes 10d10 bludgeoning damage as it is crushed by the Throne and knocked prone by it, and must remain prone until it can crawl out from under it. On a successful save, the creature harmlessly ends up on top of the Throne instead.

If the Throne expands into a space occupied by a moveable object (such as a table, barrel, or wagon), the Throne exerts 500lbs of force on the object to move it out of the way. If 500lbs of force is not enough, or the object is unmovable (such as a solid wall), the Throne butts-up against it and then tries to expand in other directions instead. If confined on multiple sides (such as in a narrow corridor), the Throne expands as much as it can and then rolls a flat 20 to "hit" whatever is confining it, inflicting 10d10 bludgeoning damage on a successful hit. This can be repeated on successive turns as long as the switch is held, until the confining object is destroyed and the Throne can continue expanding freely (see "Objects" in Chapter 8 of the DMG for guidance on inflicting damage to inanimate objects). If a roll of 20 is not enough to score a hit, however, the Throne simply stops expanding.

The mass of the Throne changes based on its current size: