This could apply to real players vs. destiny as well. Vex mind = Us. Sim = The guardians we control. Warmind = Bungie developers. (something unpredictable) So in essence, the vex we kill in game is our mind. The long hours we play in this game, the repetitive strikes, crucible grinds, shards hunting, became so mindnumbing that we became like automatons, hence vex (from another dimension). The guardians we control are the enemy but don't realize it. So when you're in the Tower and you see Guardians hoping around, sprinting and running. Don't wave, don't dance. They are the enemy. And like SHIM, SUNDARESH, MCNIADH says, you have to get out.