Cliff Climb

SPOILER

To solve this properly you need to watch the event video. At 2:51 the fireworks give you the path to climb.

left right right left right left left right left

When you make it to the top, you find a letter.

Once I got this, I looked up Percy climber disappear (since the theme of this box is disappearing)

and came back with this page Percy Fawcett

Which at the bottom has a reference to the letter pictured above with the same wording.

That brings you to the posted answer "Percy Fawcett"