- Black 15 which is a new(ish) reply to White’s invasion at 12 (well, it stopped being new several years ago, but it’s “new” with respect to the English Go books)
- The technique of playing kosumi-tsuke with 25, then directly attacking with 27 instead of defending on the right side – which of course makes a lot of sense in this case since Black is already very strong on the right side
- The order in which 13 and 15 are played is puzzling to me: not sure what other choice does White have for 14 (maybe playing at 20? or jumping to the left of 17?), and how would that affect Black’s choice of 15.
