You have to ask why Avatar 2 rescued Tu Kun. He can be saved by extracting an anti-aging liquid.

According to the content of the film, it is said in the play that an anti-aging liquid can be extracted from Tukun’s brain. Everyone thought that extracting the liquid from Tukun’s brain would make him immortal, so they all went to save him.

Avatar 2 generally refers to Avatar: Path of Water. "Avatar: Water Path" is produced by Disney Pictures, co-produced by 20th Century Pictures and Lightstorm Entertainment, directed by James Cameron, and stars Sam Worthington, Zoe Saldana, West Gurney Weaver, Stephen Lang, Cliff Curtis, Joe David Moore, Chi Pond, Edie Falco, Jaime Clement, Giovanni Ribe Science fiction movie starring West, Kate Winslet and others.