Endgame Tesuji 9

Tesuji  

aims at the connect-and-die at a, but the cut at allows Black to regain sente.

White komaster  

When White is komaster she can play with sente.

White's threat  

If Black does not protect, White can play to set up the throw-in ko with . This ko is large, as Black threatens to win it with the capture at "a", and if White wins it she has the follow-up at "b".