Sweet sounds!!!
This is a really great rockin' tune that suits the Guardian Boss well!
(For those who have trouble with it - try using attacks that hit all enemies, but focus most of your damage on the Guardian itself. Spam Air Strike and Thunderbolt, and try to keep Slime Bunny up - it will help to keep you healthy so you can spend more time actually attacking the boss. As for the Sand Worm... it's weak to Ice attacks, so use Glacier and Iceberg a lot (equip Matt with Blizzard.) You can also equip Matt with Black Fang and repeatedly use its Unleash on the Worm - it's suspectible to being poisoned, so you can just poison the thing repeatedly and then swap to Ice attacks to whittle away its remaining health - but you can heal whenever you need to, because the poison will do a good job of wiping out the Worm on its own.)