The Harlequin Crest in Diablo 4 is a Mythic Unique that can drop from endgame bosses and other high-end loot sources, not from a single guaranteed enemy. Current boss-loot guides list it among the rarest items tied to the Mythic Unique pool, and Helltide-related chests have also been reported as possible Unique sources in Diablo 4’s loot system.

Where it can drop

  • Endgame bosses with Mythic Unique loot tables are the main target farm.
  • Helltide chests can drop Uniques, which is part of why players also farm them for rare item chances.
  • Older guides and player reports confirm the Harlequin Crest exists as a very rare drop, but not from a fixed “one boss only” source.

Practical answer

If you’re asking “who drops it?” in the fastest sense: farm the bosses on the Mythic Unique table rather than normal mobs or campaign content. The safest shorthand is that it comes from the rare endgame boss pool, with no guaranteed specific dropper singled out in the sources I found.

TL;DR

Harlequin Crest drops from Diablo 4’s rare endgame loot pool, especially boss farms, and it is not tied to a single guaranteed source.