Question: why did liu kang die?
Answer: But when Shao Kahn's Outworld forces invaded Earthrealm, Liu Kang split with Raiden over how to respond. During a disagreement between them, Liu Kang was accidentally killed. His soul was collected by Quan Chi, who used it to create an evil "revenant" version of Liu Kang. He now serves Quan Chi and the Netherrealm."