Board Thread:Questions and Answers/@comment-67.142.173.20-20130504204048/@comment-98.255.144.45-20130530073732

If i recall from Vilgax Attacks (Which is an alternate timeline.)

Vilgax and Psyhon were about to kill Ben Tennyson who just transformed into Alien X,

When they both agreed to stop them they said,

Motion Deny, We shall not be destroyed.

It could be Alien X can't be killed unless they agreed to take action on what the moment of time it would take for it to happened.