aesalon: I think the avoid ko solution could be included in the problem since it is interesting.
[current position] + E2B1F1C1
To be clear, my point about C4 being bad is that C4B3 and there is no follow-up technique. That is only a little bit better than living directly with D1.
Ivan Detkov: See my previous answer. Check the current setup.
aesalon: [current position] + B17
I'm not so sure C16 should count for an advanced collection but at the very least, this should be a refutation to add.
Ivan Detkov: R4 is a bad move. It leads to a ko. I re-worked this task.
See my previous answer. Check the current setup.