I can extract health points

Li Xiao woke up and found that he had traveled to a future battlefield in another world with a billion players. Everyone became a commander with his own military base. He had to survive in a strange war world and expand his territory.
The only difference was that Li Xiao found that he could get corresponding health points for every enemy he killed, and these health points gathered in the life pool and he could use them at will!
So his infantry was like a humanoid BOSS, not afraid of gunfire and rain of bullets!
His tank seemed to have a shield, and the shells could not penetrate it, and the missiles could not bomb it!
His fighter plane became the king of air combat, killing behind enemy lines, and going in and out seven times!
His battleship turned into a sea fortress, as if it would never sink!