Some of the strangest events players can come across in are the mysterious ringing telephones scattered throughout the map. When you answer these calls, a man calling himself the King of Riddles will give you a simple riddle. Solving the riddle will give you a Trinity Key. Each Trinity Key unlocks a strange green door leading to a Trinity Sanctum.
Trinity Sanctums house special items. The entrances can be easily identified, as they are locked green doors engraved with a strange symbol. There are five Trinity Sanctums and five Trinity Keys in total, but one pair can only be unlocked after solving the previous four riddles and opening their respective Sanctums.
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The first riddle from the King of Riddles, also known as Arlecchino, appears in Krat City Hall. As you progress through the area, you'll come across a bridge leading to the Workshop Union. Instead of crossing the bridge, head right until you see a ringing phone. The King of Riddles will ask his own version of the riddle of the Sphinx. The answer to this riddle is «Human».
Malum District houses the second riddle. After a gameplay section featuring enemies on the rooftops, loop around to the area's central courtyard. You'll need to open up a gate shortcut back into the courtyard. There's a ladder just beyond this gate, leading to a small room with a telephone. The answer to the King of Riddle's second riddle is «Candle».
The third riddle found in the Grand Exhibition Gallery won't automatically give you a Trinity Key. To find the ringing phone, you'll need to activate a bridge shortcut and follow the new path. Once you tell the King of Riddles on the other end the answer is «Egg», he'll tell you to find «the cold
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