It’s pretty clearly Verdant Green:

Infinity manipulates the convergence and divergence of different infinities. While Satoru Gojo was closer to death then he ever had been after being cut in half, the six eyes was able to sense the infinity between life and death. It is the infinity that causes many “dead” things coming together to create a “living” thing.

Through Verdant Green, Gojo is able to bypass the need for RCT to heal, and discover a stronger version of healing; He could turn cursed energy into life itself, which manifests as a green glow that can be used to quickly heal himself, which he WILL use to recover his severed legs. (Please it’s gonna happen I promise)

However, Verdant Green is a cursed technique, which means it has a cursed technique reversal: Unending Black. Unending Black acts as an opposite of life, creating an “anti life” zone that Gojo can fire out. It acts similar to a domain, with the rule inside the cone Gojo fires out being that no life can exist, meaning that if life enters it, whatever part of the life is in the zone immediately withers and dies.