Firstly you will need at least two people,grab a friend or meet other guardians in the world. Once the special event starts you need to start shooting at the walkers legs (aim for the knees) until the casing falls off. Make sure you both attack from different sides ( it can only blow up one of you right?) This will deactivate the walker for time period of 10-20 seconds and it's 'head' will lower to reveal a orange glowing device, and then (you guessed it) shoot that. After it gets back up shoot at the walkers legs that still have the casing (for some reason armoured legs take more damage) and repeat the above steps until destroyed. This was a public service announcing for the Knights of the Old Earth.