Skyboom (Armada)

Formed from the Race Mini-Con Team members Dirt Boss, Downshift, and Mirage, the Skyboom is possibly the ultimate defensive force in the known universe. It is the only thing that can withstand the might of the Star Saber and Requiem Blaster weapons, but the full limits of all three have never been tested.

Linkage
The Skyboom, Star Saber, and Requiem Blaster were the "three keys" needed to awaken Unicron.

Armada cartoon
The existence of the Skyboom was first revealed by Scavenger to Megatron when the Decepticons managed to find a seemingly-unresponsive Mini-Con panel. Reputedly, the shield had the ability to resist the power of the mighty Star Saber sword.

Soon afterwards, the Decepticons managed to secure the remaining Mini-Con Race Team members, and deployed the shield in battle. To the surprise of both factions, however, when Sparkplug defended Optimus Prime, the Skyboom in turn defended the Autobot leader against Megatron's Star Saber. The resulting blows by the sword against the shield unleashed a beam of energy into deep space, similar to the Mini-Con signal that drew the Transformers to Earth.

Afterwards, the Skyboom remained in the possession of the Autobots and was entrusted in the care of Smokescreen. Smokescreen would fire the Shield from his shoulder mounted cannon in order to quickly transport it to a comrade in need.

The Skyboom was drawn toward the Star Saber. Together, they caused a signal that awakened the three Mini-Cons that combined into the Requiem Blaster.

Smokescreen/Hoist used the Skyboom to block a shot from the Requiem Blaster. He wished he had it earlier. He then handed it off to Jetfire to use on the Mars mission. While in close proximity to the other two weapons, it glowed with light and then all three caused an explosion in space.

Thrust asked Starscream to bring the Skyboom back to lunar base. He was then accused by the Autobots of stealing it when the Mini-Cons had, in fact, gone into hiding. Eventually, the kids returned the Mini-Cons to the Autobots and Hot Shot brought the shield into battle. Hoist threw it to Optimus, but Starscream grabbed shield and warped away.

On return to the Decepticons, Starscream presented the Skyboom to Megatron. It was then combined with the other two weapons into the powerful Hydra Cannon. Later, armed with the Skyboom and the Star Saber, Galvatron led the attack on Cybertron.

Betraying the Decepticons, Thrust stole the Skyboom with the Requiem Blaster to bring to Unicron. He took them through a portal to the moon and set them upon the ground.

The Skyboom was then considered part of Unicron's body, with tentacles covering the shield and the component Mini-Cons being unable to wake up until the Mini-Con song was sung,  at which point, the Skyboom then flew out of Unicron.

Transformers Legends comic
Megatron wielded the Skyboom, Star Saber, and Requiem Blaster during his foray into the Legends Universe.