XYZ-Wing

Expert Used by Smart Hint

A three-candidate cell links to two two-candidate cells whose combined candidates match it exactly — the shared height can't be in any cell all three see.

Cells that establish the pattern
Where the conclusion lands
Height ruled out

How it works

An XY-Wing whose pivot keeps a third candidate: {1, 2, 3} here, with wings {1, 3} and {2, 3}.
Now the pivot itself might be the 3, so the guarantee widens: one of the THREE cells is a 3, not just one of the two wings.
That means only cells seeing all three can be eliminated from — and here all three sit in one row, so those are the row's remaining cells. Strike their 3s.
Worth knowing the limit: Skyscrapers has no boxes, only rows and columns. Work it through and a common peer of all three exists only when all three share one line — and three cells in a line covering three heights is a Naked Triple, which this guide lists as easier and which strikes all three heights rather than just the shared one.
So in practice the Naked Triple gets there first. The shape is here because you'll recognise it from Sudoku, where boxes give it room the Skyscrapers grid doesn't.