After many wasted hours we finally managed to fine tune our approach against Crota. Beauty was this... When we beat him we all changed characters to try and defeat him again. We managed this again in 1 flawless attempt. Two consecutive attempts, to me, means we have an effective process. My lessons learned are here. My point is to try and help other Guardians who have lots of failed attempts. 1. All about your sword bearer. It is critical you have someone who knows what they are doing with the sword. All being good you will probably have to hit Crota 5-8 times (each with multiple strikes). 2. Invisibility between attacks with sword against Crota. Our process was to use a hunter with invisibility perk. After hitting Crota once we then dropped the sword and melee'd him to turn invisible. This meant there was almost zero lead time between taking him down a second time and starting to strike him again. This maximises the damage and minimises the take down quantity requirements. 3. Don't take Crota armour down too early. Wait until he the sword bearer is close to Crota and co-ordinate the attack. Failure to do this means your window of attack can be minimal which in turn means you need to take him down more times. 4. Don't hit the sword bearer (enemy) too early or with sniper rifles. For us, 80+% of the damage against sword bearer occurred when he was close to us. Wait for him to get close then start attacking. Failure to do this means it ultimately takes longer to take him down which in turn can lead to Crota moving location. (Timings unrelated). We also found hitting him with special weapons made him move backwards. I am hoping to get the same team together tomorrow night and taking him down again, twice, in perfect succession. A lot of this is probably already out there but I hope this helps fellow Guardians.