The Guardian who undertook that task goes by the gamertag SerfaBoy. As can be seen in this sped up record of his journey to Level 40, this method takes a lot of grinding.

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It took SerfaBoy 2,137 runs through the first mission, called “A Guardian Rises.” That comes out to 98 hours and 13 minutes of playtime, according to the internal time counter in Destiny. But that only counts actual time in the game, not loading screens. The total time estimated by SerfaBoy, saying he could keep each run to three minutes, was 106 hours 51 minutes.

To level his character, it took a total of 265, 194 experience points. Here are some more stats from his run:

62,674 enemies killed 27,256 primary weapon kills 16,918 special weapon kills 11,605 heavy weapon kills 6,847 ability kills 5,280 grenade kills 1,567 melee kills 19 deaths 3,298. 63 KD Ratio 90 Orbs of Light generated

That’s a lot of Dregs killed. His most used weapon was unsurprisingly the first gun in the game picked up during that mission, the Khvostov 7G-02.

SerfaBoy acknowledges that completing this challenge was a bit of a waste of time, but was fun nonetheless:

This feat would not have been possible before The Taken King when Light (gained from gear) was tied to a character’s Level. But in The Taken King those bonds were broken and Light Level staying gear-based while Character Level became experience-based.

This is another example of hardcore Destiny fans finding ways to challenge themselves and tackle old content in new ways while waiting out the current content drought. Although, Bungie gave fans something to look forward to yesterday, laying out a roadmap for a Spring Update in a few months, and news of a major expansion later this year and a full sequel in 2017.

Source: Destiny Reddit