The 1-2 point prevails over the 2-2 point again.
There is no way White can attack Black. The distance between and is wide enough for him to make a second eye (the circled point).
If Black omits , White kills:
If Black carelessly plays at the 2-2 point, White takes the vital point with and sets up an approach ko. Black can't block at a because of shortage of liberties. So he has to fight the ko at . After White recaptures the ko ...
So, White has to play an extra move, and if Black loses the corner, he will have played twice elsewhere in return.
Anyway, living unconditionally is much better for Black.
Enlarging the eyespace with is dubious. After , Black has to defend his cutting point with . Further enlarging the eyespace with forces and now White can either play atari at a in the future, or if Black plays there, almost fill Black with a farmer's hat by playing at b.
Fancy play at doesn't help much. After on the 2-1 point, White can answer with , preventing any escape. Black has only one eye. Now and are miai points.
Black does better to try to run with , eliciting . Now sets up a ko.
leads to a throw-in ko.