Advent ability, RESURRECTION, please help

When one of your capital ships dies and the Progenitor is in the gravity well, the Progenitor will "store" the destroyed Capital Ship's level (let's say 7) if it has Resurrection.

Then, if it casts Resurrection, on say, a level 2 Capital Ship, the level 2's crew basically become the destroyed level 7's crew, causing it to become level 7.

Advent are known to have the best late game though.

This is a common misconception that shows just how little people understand this ability (not to pick on you Mr. Haze).

The mothership does not have to be in the gravity well. If you had a level 10 Radiance battleship that gets destroyed anywhere in the galaxy, and you then build another Radiance at your home world with a level six Mothership orbiting it, if you use Resurrection on the Radiance after a moment it will be promoted to level 10. If you had a level 6 Halcyon then die, if you rebuilt a new one and used resurrection on it, the new Halcyon would be level 6. If you built a Rapture but haven't lost one, it will do nothing. If you built another Radiance before the level 10 one was destroyed, it would also do nothing.

I'm a little bit fuzzier on whether the mothership needs the resurrection ability before it start keeping track of if you lose multiple say Halcyons and then try to use resurrection on multiple rebuilt ones, but its a powerful ability for Advent late game that most people don't use to their advantage.

No offense taken, I like learning. I just very, very, rarely have the chance* or need to use that ability.

*Read: Everyone shoots the Progenitor first.

To add to what Goa already explained: This ability also works when you have a capital ship of any kind without owning a single Progenitor Mothership. To make myself clear: Let's say we have a level 7 Halcyon Carrier. It dies in combat. Now I build a Progenitor Mothership. I play with it for about 2 hours, get it to level six and unlock the Resurrection ability. Now I build a new Halcyon carrier. I cast Resurrection on it with my Progenitor Mothership and voila, it is now level 7. So even when your capital ships die before you have built any Progenitor capital ship at all, this ability is still useful.

So remember that it is always a good investment to build a Progenitor Mothership when you have lost multiple higher level capital ships earlier during the game!

can the spirits of the same ship be resurrected more than once?

i.e i lose one halcyon and use it to promote two that i built afterwards?

I highly doubt it. Those spirits can't be two places at once, after all.

No. If you had a level 10 Halcyon that you lost, you can only use that to promote one Halcyon to level 10.