Introduced in the very first Xenoblade Chronicles game, Unique Monsters are a staple of the series, represented as powerful monsters for players to try and take down for added challenge.
Many-Lived Derrick is a Unique Monster that appears in Xenoblade Chronicles 3: Future Connected. It can be found near Gelgemos Garrison in The Ragmos Desolation and defeating it counts towards completing your Enemypaedia.
Many-Lived Derrick (Level 42) | The Ragmos Desolation
For assistance with finding all Unique Monsters in The Ragmos Desolation, why not check out our useful guide below:
[Guide] The Ragmos Desolation Unique Monsters | Xenoblade Chronicles 3: Future Redeemed