Edge template IV1c
Red has two main threats:
using the ziggurat.
For trying to block the connection Blue has to play on the overlap:
Red 2 threatens to connect to the bottom on the left side and forces a Blue move like 3. Likewise Red 4 forces 5 or similar moves. In the end 6 is safely connected via 2 or 4.
Now white has three main threads:
using the ziggurat and
where the group containing 1 is connected to the left via one of the spots marked with + and trivially to the bottom.
The overlap in which Blue has to play:
The 4 different moves are now considered from top left to bottom righ:
Move 1 (g3):
The group containing 4 is now connected to the bottom via the template III-2-b
Move 2 (g4):
The group containing 4 is now connected to the left by one of the threads marked with + and to the bottom via the template IV-2-b
Move 3 (f5):
If Blue plays 3 before 5, Red can play 4 before 6.
Move 4 (g5):
So all Blue blocking attempts fail.