kovarex:
+ S1 It almost looks like it is killed now, where did black make the mistake?

posetcay:
Added refutations to C19-C18-B19, double-ko solutions are marked as incorrect now.

Hrewsahgs:
Sorry, I should've been more specific. It's not about the local position specifically, but about how the attacking side gets to become komaster/komonster with a double ko threat, despite the defending side being able to avoid such a scenario. Is that not a valid enough reason?

Hrewsahgs:
Not sure why this line is considered correct, considering a clean kill is possible.

Lyde:
After R19 R18 S19 S16 the moves S18 and Q18 also work

posetcay:
Added R19-R18-S19-S16-S18 as an alternative.