What is The Odd One challenge in Destiny 2: The Witch Queen?

gamepur.com:

As you progress through the Destiny 2 expansion, The Witch Queen, you’ll encounter a series of riddles and puzzles you’ll need to solve. During two points in the story, there are two quests where you have to solve a particular puzzle surrounding Savathûn’s Memories. If you stand there long enough, you’ll receive a notification that says, “The Odd One Challenge.” This guide covers what The Odd One Challenge is and how it works in Destiny 2.

You’ll see the notification for The Odd One Challenge if you’re stuck on the Memory mission during The Witch Queen expansion. We have it pictured below for you.

Essentially, the notification serves as a hint regarding what you need to do in this location. During this part of the mission, your goal is to shoot the correct rune, which should appear different from the other runes displayed on the alter. You need to shoot the right rune to proceed through the quest. The rune will vary based on your rune choices, and the answer varies for all players, so we can’t list out which ones they’re going to be. You’ll know you’ve hit the correct rune if you see a green glyph appear above it.

There will be three runes you need to hit for each of the puzzles in The Witch Queen expansion. Once you hit all three, you can progress through the story. For those who are stuck, it doesn’t hurt to shoot all of the runes until you identify the three runes individually and then shoot them all to progress. You’ll have to remember which ones they are, though.