Legendary ending, what does it mean?

Firstly I only completed it on legendary and by myself so assuming the ending was a legendary ending after credit’s. Anyway it sounded like a hum by another monitor, doubt it’s guilty spark, even he survived getting shot by a Spartan laser, the ending seemed heavily focused on the Halo ring, makes me suspect the return of the Flood.

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> Firstly I only completed it on legendary and by myself so assuming the ending was a legendary ending after credit’s. Anyway it sounded like a hum by another monitor, doubt it’s guilty spark, even he survived getting shot by a Spartan laser, the ending seemed heavily focused on the Halo ring, makes me suspect the return of the Flood.

Guilty Spark is still alive and kicking, it’s shown in The Forerunner Trilogy.