If the Rainstorm Pear Blossom Needles were a large-scale, crescent-shaped hidden weapon, almost impossible to evade, then the Life-Locking Needle was a small-scale hidden weapon that, though easier to dodge, was far more lethal.
The terror of the Rainstorm Pear Blossom Needles lay in their inescapable fan-shaped attack. The twenty-seven silver needles were immensely vicious, ensuring that each release drew blood. In contrast, the Life-Locking Needle's terror was in its absolute fatality—if it hit, death was guaranteed.
The phrase "Three Thousand Ways to Kill" wasn't mere bluster.
If Ryven had still been at his peak, Aizen wouldn't have dared rely on the Life-Locking Needle to kill him. But now, Ryven's strength was no longer what it used to be. Moreover, his recent display of such a high-consumption ultimate technique, while heavily injuring and forcing back Gideon, also provided Aizen with an unprecedented opportunity.