Honestly, I'm not sure why I'm proposing this idea. It brought me as much frustration and irritation as it did enjoyment. However, it truly is something that I find enjoyable in gaming, and something I had hoped to see in Trove.
I've been gaming a very long time now. I started back in the days of MUDs, The Realm, Meridian 59, etc. I still consider EverQuest a relatively newer game even though it's nearly two decades old now. One of my favorite periods of gaming was in the early days of EverQuest, when the devs would plant relatively complex mob spawning patterns that ultimately lead to rare spawns that had a small chance of a rare drop. Take for example my personal favorite (and most hated) - Pyzjn. I camped that horrible gnome woman for hours upon hours, always hoping for a GBS (Glowing Black Stone). Finally, I scored one, but it took ages. There were loads of rumors about how to get her to spawn... by killing random named trash within the zone, etc.
Regardless, my point is this... I'd absolutely love to see something similar created with Trove, where certain biomes have a very small chance of spawning unique mobs that have a small chance to drop a rare item... maybe something as simple as a style or a recipe, or maybe even a unique Shadow or Radiant item or something.
I also wouldn't be against seeing those items tagged as non-tradeable (or No Drop, using the old EQ lingo). That way the few people willing to work on finding those mobs have something unique to show for their work.
I'd like to see these mobs appear somewhere other than dungeons. Maybe make then simple roaming mobs that wander the landscape of a biome, thus forcing players into new areas and out of the ubiquitous dungeon crawl. Or... maybe a rare spawn dungeon entrance that leads to a unique dungeon with a boss or mobs that have a chance to drop rare items, like recipes, styles, etc.