What was your first Boss & Jumping Puzzle?

The first big boss and Jumping Puzzle that you encountered when you first started playing?

I wondered into the Fire Elemental, back when it was still really hard. I couldn’t believe how many people were there. Everyone – including me – kept dying. It was crazy.
Next one was Tequatl, I didn’t realize that there were dragons to fight. Mind Blown!
 
My first jumping puzzle was the Fawcett’s Bounty. I found the entrance then kept dying through the caves. Once I got to the ship, I kept miss jumping. I think I was in there for over 2 hours. I was determined to get to the ship. Finally did with help from someone going through it too.