Incineration Cannons on Forerunner

The Incineration Cannons on Forerunner is an Easter egg found on the Halo 4 mission Forerunner. It can only be found on Legendary difficulty. If the easter egg is performed correctly, it spawns nine Incineration Cannons.

Walkthrough
Start up the mission Forerunner from Rally Point Charlie. Upon loading the mission, grab the LightRifle and Scattershot in order to more easily deal with the enemies, and stock up on ammo for these weapons. Play through the level normally, all the way to the valley where a Promethean Knight is seen slaughtering Ghost-riding Sangheili. Destroy him and take any one of the vacant Ghosts.

Again, play through the next section of the level normally and destroy every Covenant and Promethean enemy available, all the way up to the entrance to the second pylon. Dialogue should play after all the enemies are killed. Now backtrack to the previous area. As a precaution, though, kill any and all remaining enemies that may have been missed, especially Promethean Watchers, so as to avoid making the next step of this easter egg more unnecessarily difficult.

Next, climb up one of the high-rise rocks near some of the Individual Breaching Carapaces, crouch, and wait for five seconds. A group of five Scattershot-wielding Knight Battlewagons should appear. Immediately retreat up the hill and take cover using the rocks to avoid being severely damaged by the Knight Battlewagons' weapons. Always use the Autosentry, as it is very helpful in killing the Knight Battlewagons. The LightRifle and Scattershot are effective at killing the Knights at range and up close, respectively.

Once the fifth and last Knight Battlewagon dies, return through the doorway. Nine Incineration Cannons will fall from the sky.