And here we see an excellent motivator for elves to seek adventure out of their utopic homelands.
And, visitors could get a major introduction in elvish culture once they inevitably fall into the 'servitor' role, as the elves, happy for something unusual in their lives, make the outsiders run all manner of errand in the city. Their unfamiliarity would likely lead to still more infractions making it harder to get out. Maybe they eventually cause enough chaos and disruption that banishment becomes a better alternative and that's how they break the cycle.
Purple deer have begun to appear near the ruins of a fallen city, or other place of power. Hunting the deer is absurdly easy, as their coloration makes them easy to see. The heros prepare a feast from a freshly killed deer find out several hours later that the meat of the new purple deer is poisonous. This can range from cramps and vomiting to the truly sinister and lethal.