This trap hurls large objects at the unsuspecting party. This is a rather obvious trap, but it’s great for visual effects and will almost certainly be triggered due to the treasure it offers.
The amphitheater itself is dominated by a crouching statue that bears a huge globe upon its shoulders. The globe is roughly 5 feet in diameter, and weighs in the neighborhood of several tons.
The amphitheater’s floor is an enormous, finely balanced lever. Whenever a weight is set upon the floor (such as a party of adventurers), the lever shifts, causing the pole within the main amphitheater structure to rise and dislodge the golden sphere. The ball bounces down the steps and into the midst of the party.
The globe itself could make quite a prize, depending on its material makeup (gold vs stone) and/or contents inside, but getting it out of the dungeon is tricky. Reducing it to a more manageable size would ruin the sphere’s quality, likewise, reducing its value.