This is how Iacon Destroyed goes in Connor Lacey's Super Adventures of Transformers: War for Cybertron.
Narrator: HUNGRY FOR MORE POWER, MEGATRON PLANS TO CORRUPT THE VERY CORE OF CYBERTRON ITSELF WITH DARK ENERGON. BUT TO DO SO, HE MUST FIRST FIND THE OMEGA KEY, WHICH WILL UNLOCK THE GATEWAY TO THE CORE. MEGATRON LAUNCHES A FULL SCALE ASSAULT ON IACON, CAPITAL CITY OF THE AUTOBOTS, WHERE THE KEY IS PROTECTED BY ZETA PRIME–LEADER OF THE AUTOBOTS.
[The story begins on Iacon]
[The Decepticons are heading to Iacon in a dropship to get the key from Zeta Prime]
Megatron: Decepticons, the Autobots