Disruptor cannon

This really seems like one of the other Megatron's schemes.

The disruptor cannon is a really big cannon in a cave, which Megatron intends to use to blow up the Ark. As plans go, it's not one of his more complicated. At full power, the cannon can cause Cybertronian bodies to explode.

Fiction

Beast Wars cartoon

Megatron had the cannon built in a mountain-top cave, with line-of-sight, but still a fair distance away from Mount St. Hilary. While the Predacons were in the process of putting the finishing touches on it, someone plugged in the bi-polar energon source before all of the shielding had been installed, resulting in energy surges which prevented the Predacons from approaching their own weapon.

As the surges only affected mechanical life forms, Waspinator and Inferno were dispatched to kidnap the young anthropoid Una and bring her back to the cave. As they returned with Depth Charge and Rattrap in hot pursuit, Megatron fired the cannon on its lowest setting in order to knock the two Maximals out of the air. Feedback from the firing also zapped the Predacons, making the installation of the shielding ever more urgent. Megatron instructed Una on doing so, and got her to install the vital stabilizer crystal. Though Una subsequently escaped, the cannon was finally ready. Savoring the taste of victory, Megatron prepared to fire on the Maximal base.

Unfortunately Una had not installed the stabilizer crystal after all, and the cannon exploded, taking most of the mountain with it. Go with the Flow