Secret Sentinel

Not to be confused with the Guardian called The Secret Sentinel.

Secret Sentinel is the final level and Guardian level in Croc: Legend of the Gobbos and the only Guardian of Crystal Island. It is the forty-fifth level the player reaches and upon completion will complete the game 100%.

Walkthrough
The trick to defeating him is to have all four Beany Gongs ringing at once. Each will continue to warble for a short time after hitting it, giving you time to get around to the others. If you take the floating platforms, however, it'll take too long. Instead, you can just jump from alcove to alcove across the corners. Grab at least one crystal at the start and strike the first Beany Gong, then pick a direction, left or right. Jump across the corner to the next alcove and strike the Beany Gong there, then continue in the same direction until you've hit all four.