Directed Slipspace Weaponry

Of all the weapons created by the Forerunners, few are as devastating as the DSW, or Directed Slipspace Weaponry. Created as a last resort during the titanic Forerunner-Flood war, the DSW was highly controversial in Forerunner culture, but also showcased the race's incredibly advanced knowledge of slipspace.

Creation
After the creation of the gargantuan keyships (which would be used to transport and index different species and bring them back to the ark, the Forerunners began creating several new military weapons to help defend these ships from the flood. The Forerunners, knowing that they would need to pull out all the stops in order to defend the ships (the Keyships were likely to be juicy targets for the flood) decided to create the most magnificent weapon they had ever assembled, aside from the halo array.  This new weapon would be a device capable of tremendous devastation.

Operation
The DSW had a form of operation unique unlike anything the Forerunners had ever made. As its name suggests, it used slipspace as a offensive weapon. The weapon was not fired, not in any traditional form. It did not use plasma or ballistics, nor any other type of chemical, nuclear, energy, or biological weapon. It instead used slipspace itself. The "weapon" was actually a slipspace projector capable of creating a slipspace field in an area up millions of kilometers away that was accurate down to the atom. The weapon would create a field inside an enemy ship or vessel, and then energy pulses would strengthen the field. This strengthening would make the field "suck" all matter into slipspace with frightening speed, destroying the vessel. Later, more powerful versions could destroy entire planets, or even larger planetary bodies, like gas giants or stars.

Usage
The weapon, due to it's controversy, was used only rarely in combat. Even against the evil and hideous flood enemy, the forerunners disliked using it. As a result, it was only used three times. However, all three times resulted in stunning forerunner victories, and tremendous destruction. It's final use was in Offensive Bias' battle against Mendicant Bias, and during the battle, it was extremely effective. After the Halo Effect struck the galaxy and all sentient life was obliterated, the weapon was presumed lost. However, when human EABT teams infiltrated the Forerunner Dreadnought during the Battle of the Ark, they downloaded several files that had eluded Covenant scientists for centuries. The UNSC and Separatists were successfully able to comprehend the weapon and they learned it's history, but were never able to recreate it.