I was looking for an easy way to figure out which void relics to use if I wanted a certain part. It may be somewhere else on here, but I found this in someones google sheet and copied it out. It includes the part, the rarity, the relic tier and name, and also if it is vaulted. https://docs.google.com/spreadsheets/d/1c_W9OTTPUjP3oiNvGYbsE2p8hVB0lUDjfUk83NRmDHU/edit?usp=sharing
now that's useful. Even if it's not perfectly accurate it'll help reference where you might start looking.
Excavation missions seem to be pretty decent for getting relics as well. I haven't tested out the interception missions since that's a bit of a pain solo.
These are missions that are good for getting the Relics so then you can run relic missions and unlock prime pieces.
interceptions are actually a good one to pug because it's very rare to completely fail, and you typically can tell you're struggling long before you actually get to a point where you can't win. The only way the enemy can win is by simply overwhelming the team.
I remember reading a post where someone said they did the Venus interception for 12 rounds, got 11 relics and the enemies were only up to lv 15 or so at the end. I haven't tested it so I can't confirm, but that sounds damn good.
it's not impossible, I'm not sure about the level of enemy at that point, but even just going to 4 for the c rotation reward should be simple enough
Soloing interceptions seems easy when you're a limbo as long as you're good at keeping track of multiple positions.