What the Key Unlocked - S2.E2

When Merlin is asked why Bog Lake is boiling, he learns that the key Lance can use to free Sir Lancelot is within. Tone creates a portable shed with scuba equipment of vines so Artur and Lance can search for it. The three, Wally, Brick, Breeze, and Lug avoid the Warlords on their way out thanks to a Merlin's decoy, but Morgana learns of the key about the same time the Warlords realize the trick. The Warlords attack just after an underwater chasm opens and the key falls in, and cut Lance's scuba so he topples in as well.