... to answer your question, when it came time to reach out, to find a Guardian to take on this mission, there was only one choice.
- They stood against the Vex in the Black Garden, and grounded that place to Mars.
- They went against the Hive in the dark below, working with Eris Morn to undermine Crota, the Hive God.
- The Reefborn made use of the Guardian in their search for the criminal Skolas, as I understand.
- And, of course, it was the Guardian that led the assault on the Taken King's Dreadnaught.
All of the after-action reports I've shown you about the Taken War, the calm state of the system... we have this Guardian to thank.
I've attached more details, if you want to read evaluations from the Vanguard. Just skim Cayde's. He's... not very biased, here.