If AntiTristan killed Tristan the loss would be a another big blow to both the Atlantean army and Anti himself.

If Tristan was killed then not only will AntiTristan not have a host to torment it would banish him to another dimension known as Outworld where the forgotten resign.

If AntiTristan killed Tristan he would be so upset he wouldn't even try to fight Dark Martin or Digger if they challenged him he'd just drop his knife and raise his arms in a gesture of giving up, that's what would happen if AntiTristan killed Tristan