Definitely the easiest of the 3 new Archives challenges. It’s basically just Expert mode but you can’t use close-range heroes.
I got this on my first try playing as Bastion with a random group of people playing a Mercy <3, a Phara, and a Widowmaker.
Just staying on the high ground when I could and falling back behind cover if I was taking too much damage.
The only really tricky parts are the Big bullet sponge brutes that drop in the warehouse and 2 that drop before the end of the mission. The warehouse one can be beaten pretty easily as long as everyone keeps their distance. The last 2 can be tricky, however you can totally cheese the last fight by going on the 2nd story floor with the broken wall that’s across the bridge. When you bring the cart near it an enemy will kick in the door, once you take the cart to the end you should go back to that room and just wait it out while shooting all the enemies that come past the bridge. The big brutes will come up the stairs and you may need to jump off if they reach the top, but you can easily circle around them and go right back up once you’ve lured them away.
*Edit: Sometimes the normal enemies won’t spawn and kick in the doors and you’ll have to fight an Assassin instead. If that’s the case just deliver the cart and head back across the bridge so you can funnel them in.
OR
You can prepare ahead of time and have one teammate as a Symmetra to teleport up there, or as a Mei and Ice Wall your team up into the room. Either way works out great because the enemies have NO POSSIBLE WAY to get up there. So you’d only have to worry about an Assassin and might have to leave it to kill the Snipers, but other than that you’re golden!