Rock

"You expected a reward beyond this mere pebble? Patience, the true reward will come apparent in time..."

The Rock is the player's reward for beating the Boss Rush. Despite the challenge required to obtain it, it has no real purpose other than being a trophy for completing the Boss Rush.

Trivia

 * It only sells for 1 copper coin. Because of the fact that the bosses do not drop any loot or money at all during the event, this makes the Boss Rush one of the hardest (if not the hardest) ways of making money in the game.