Raito Raito no Mi/Jigoku Hari

Jigoku Hari
Jigoku Hari (地獄針, Literally meaning "hell needles") was created by Renji in his effort to concentrate light stored in his body to the fullest extent to somehow form weapons that are made of light and have piercing properties, after concentrating the light as much as he can, Renji eventually failed and ended up with nothing more then a needle made of exetremly concentrated light.

These needles were incredibly hot due to the extreme concentration of light in them, after that Renji decided to find a way of using them in battle, he came up with the idea of conjuring up four of those needles one from his index finger and the other from his midlle finger from each hand, and fight by piercing enemies with them, after Renji pierces an opponent with these light needles, the extrem heat of those needles will literally burn the inside of the target's body causing severe internal damage, Renji usally targets vital organs with this technique to finish off opponents quickly, after piercing opponents with these needles several times, they will eventually lose their energy and disappear. After the timeskip Renji learned how to fire these needles at targets with extreme accuracy and precision for long ranged attacks.

The technique however has one major weakness, as it greatly affects Renji's stamina after prolongued use.

Before the timeskip
At this time, Renji had a hard time concentrating that much light into such a small needle, the technique would also greatly effect his stamina and deplete his energy, because it requires massive amounts of light.

After the timeskip
It is much easier for Renji to preform the technique now, he now gained much more control of the technique and learned how to fire these needles at targets with extreme accuracy and precision and speed even from great distances mostly for targeting their vital organs. The incredible speed of these fired needles is what makes it very dangerous.

Renji now can repeatdly use Jigoku Hari and for longer periods of time with less effect on his stamina.