Lithel: Playing at makes miai of a and b.
Lithel: The chain of black stones can not be cut at the upper left since a and b are miai for connecting and c can not be played without the supporting move at d.
Lithel: The chain of black stones reaches all the way around in order to form life. This position is known as a Two Headed Dragon.
Lithel: Attacking the corner doesn't help either, since Black will still be able to form a real eye due to the outer stones wrapping around. Another Two Headed Dragon.