kinda personal...dyt ?
What is your favorite endgame position

many rook ending positions are great to study from both sides the weaker for drawing chances and from stronger side to win
They include Lucena Philidor Passive rook position and Rook vs pawns on same side.

cjxchess17: Seems like my puzzle got an inspiration from Tim Krabbe's original from the early 70s.
1. e7 1...Kxf3 2. e8=R 2...Kg2 3. 0-0-0-0#
You castle vertically with promoted rook to deliver mate in 2.