Unique. Troll. 1 strike. Also playable at Moria and The Under-gates. If Doors of Night is in play, playable at any Under-deeps site. Any non-unique Orc or Troll hazard creature can be played (not counting against the hazard limit) on a company that has faced Bûthrakaur that turn.
"The Uruk flew to the floor and offered the troll-king anything and any kin in return for his pitiful salvation."
-Kuduk Lore