In the animation, as the two star fleet space ships get close to the ground, a hidden doorway (looks like) from the ground emerges and flips open. I decided the skull shape as the skull represents the antagonist. From the door, the alien space ship emerges out and tries to flee.
The Enterprise chases the alien ship and Indegro lands on the ground from
where the skull emerged, during the chase Enterprise fires the torpedos and like other episodes I made the torpedos split
after a few seconds, one of the torpedos misses its aim but the other one hits the exhausts that blows the alien vessel