Basically Perfect Raider alone. Doing a raid without a single member of your team dying is very, very hard and very, very luck-based (the section in Vault of Glass where you need to platform alone has people missing a jump and dying all the time, negating the entire run, and that isn't even a fight). I suppose with the level increases it will get easier over time, and obviously with practice a group of people can memorize it and get it done, but it's not easy in the least.
I know this might be a stupid thing to ask, but is Destiny really a 10/10 to complete? That seems REALLY high as the other games with a 10 (that I know of) are DmC 4/HD, Ninja Gaiden II, and Akai Atana (spelling?). What about it makes it a 10 is what I'm asking, since Dark Souls and Metal Gear Rising: Revengeance have 8 and 9 respectively.