Instructions
Complete "Shadow of the Colossus" in regular mode and save your game.
Re-open the saved file in which you beat the game.
Press the circle button on the controller. This will cause you to pray to the Colossus statue. You will then be in "Time Attack Mode." You will be given 9 minutes and 30 seconds to defeat as many Colossi as possible.
Run around and defeat all of the Colossi you see. You will receive rewards for defeating them while in Time Attack Mode. Defeat two for a Whistling Arrow; four for a Cloak of Force; six for a Mask of Strength; eight for a Lizard Detection Stone; 10 for a Fruit Tree Map; 12 for a Mask of Power; 14 for a Cloak of Deception; and 16 for a Flash Arrow and Brown Agro.