Once Nevalden Rehn has the crate of marks, you can get some from him at any time. They aren't lore so it's recommended that you grab as many presences as you are currently seeking. Grab 3 to start out with.
In order to rescue the Vah, you need to kill certain areas of a zone. The presences do NOT spawn off just anything in a given zone and some are rarer than others. If you're in the right area, every mob you kill has a chance to spawn a hidden presence upon it's death. If you're flagged to rescue the Vah in that zone, hailing the presence will allow you to spawn the actual Vah you were sent to get. Once you have the real Vah in front of you, talk to it and give it a Mark of the Vah so it can leave.
Don't get discouraged if you can't get one to spawn quickly. And if you're a short race, learn to look up. Presences don't actually have a character model but they are tall. They're just a floating name and are usually well above a short race's head so they're kind of easy to miss. They also don't necessarily spawn the very instant a mob dies. This isn't a big issue if you're pulling all the mobs to the same spot, but if you're just roaming around and killing everything in your path, one might spawn behind you without your notice. The hidden presences only stay up for 5-10 minutes so be sharp about it.
Walkthrough
Find Nevaldan Rehn (Southern Waste of Tarhyl at -1240, 1290, -22 • Vah Camp) .
You say, 'Hail, Nevaldan Rehn'
Nevaldan Rehn tells you, 'Thank you for bringing Mira, Araghin, and Ryhajin to us, <Player Name>.' Nevaldan favors you with a small nod. 'We are in your debt.'
You say, 'I hear a lingering 'however' in there.'
Nevaldan Rehn tells you, 'Indeed you do. We've just received word of another vah in Siren's Grottos, and it's urgent. You must hurry there, find her as quickly as possible. She's not in good shape.'
Your journal has been updated. [The Vah]
Journal Text: I found the first wave of vah refugees. Nevaldan has told me of another in Siren's Grotto. I must hurry there and rescue her. If I need another Mark, I should speak with Lyjan.
Receiving Additional Marks
Note: You can request as many Mark of the Vah as you need from Lyjan at any time.
Find Lyjan Vahl (Southern Waste of Tarhyl at -1280, 1270, -23 • Vah Rehn Camp) .
You say, 'Hail, Lyjan Vahl'
Lyjan nods, flicking an ear at you.
You say, 'I need another mark.'
Lyjan removes another amulet from the crate. He cleans it for a moment, then begins to tell it of the fate of the vah.
You say, '-Let him finish.-'
The shade flees from the mark. The metal lays inert in Lyjan's palm. He closes his fingers around it, claws digging into his palm. 'There's no time for mourning. Vah are still lost out there and they need to be shown the way. No grand cities, no art, no science or culture, tents only, yes. No future, no hope. A beaten people. But people still. Is it right that vah should die alone?' A hint of wavering light shows through the fur between Lyjan's fingers. 'If you and I and our oaths are all that's left, so be it. When we go, it will be as Vah *Shir*. Our people are here and our duty is here and we will serve both until we all pass and the sky is empty again.' The light steadies, pulses once, then fades. Lyjan turns to you and places it in your palm. 'It has been bound to this place. It will do its part as long as it is able.'
You receive Mark of the Vah from Lyjan Vahl.
Complete Saving Shaylan Nairu.
Return to Nevaldan Rehn (Southern Waste of Tarhyl at -1240, 1290, -22 • Vah Camp) .
You say, 'Hail, Nevaldan Rehn'
Nevaldan's ears flag a little when he sees you. 'Thank you for rescuing Shaylan, <Player Name>, but I sense from your expression you'll not be satisfied with just gratitude.'
You say, 'I'd like some answers, Nevaldan.'
Nevaldan sighs. 'I'll tell you what I know, <Player Name>, but it's precious little. It all ties back to this 'traveler' woman--everything we know, we learned from her. She tells us where to find the refugees. I don't know why she's chosen to come directly to our camp now, but it has something to do with Shaylan. Past that, we only know that she's very interested in us but otherwise values her privacy. And <Player Name>... without her, we'd have no way of locating the refugees in time to save them. Whatever you do, don't jeopardize that.'
You say, 'So I should talk to the traveler if I want to know more.'
Nevaldan Rehn tells you, 'Exactly. She isn't here now, but she said she'd be back before long. For now, she's told us where to find more of the refugees. There are four more: One in Fire Grottos, one in Everchill, one in Highhold Keep, and one in the First Ruins. Oh, and one other thing, <Player Name>.'
Your journal has been updated. [The Vah]
Journal Text: I've learned from Nevaldan that the traveler is the source of his knowledge of the vah. If I want to press the issue, I can speak with her. Past that, there are more refugees to rescue: In Everchill, Fire Grottos, First Ruins, and Highhold Keep.
You say, 'What's the other thing?'
Nevaldan Rehn tells you, 'I spoke with Lyjan at length about this. It took some convincing, but he agreed. Here, take this. You've more than earned it. You'll still need to see him to get Marks to give the refugees, but this time you'll have one for yourself, too.'
You receive Mark of the Vah from Nevaldan Rehn.
Your faction standing with Vah Rehn Survivors has gotten better!