Panoptes was a really cool boss that had the misfortune of being in an underwhelming DLC. His design was awesome and intimidating, and the fight was very cool thematically. People often ask for "single player raids". Panoptes was a single player raid boss. Add one or two more mechanics and he'd fit in with any other raid boss.
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The power that Panoptes and Xol had should've 100% made them Raid bosses. Instead they're just... a story boss and a strike boss. Huge missed opportunity for a raid in the Infinite Forest and one on Mars.