Neferneferuaten / Responding to hopeless invasions
Invasion by attaching to a stone
Let's consider this invasion.
Black is attacking a lone third line stone, so our immediate reaction should be to extend while blocking.
Defcon 5
If left undisturbed, white may try to make a base with `a` or gain corner territory with `b` or `c`.
If it gets to this point, katago recommends blocking, then invading black's eyespace.