Displacers Help?

looking to clear tav and aht urghan t1 soon and i plan to shout for ppls. thinking i will use displacers; never have.
main goal is to get 100% white for the periapts/etc.

1 enough for each mob?
how many can i use on a mob?
does it just lower their hp or?
can multiple ppl trade displacers to a rift?
any other info that you can provide is much appreciated!

Fjalar and Yalungur are the only 2 mobs that are likely to cause you some trouble if the alliance isn't performant.

Dimgruzub could also cause issues in case of bad procs, but it doesn't really need any displacers if you manage to keep it procd and avoid charm etc.

Theoretically you could use up to 5 displacers per mob, but I'd say neither Fjalar and Yalungur require more than 2. Iirc the way they work is they reduce the mob's stats overall, not just the HP, proportionally to the amount of clusters you use. Idk the exact value or percentage.

Only the guy poping the NM can trade his displacer > void cluster, so it usually is the tank's role due to several of those mobs spawning with adds.

0-2 Should be enough for each NM
1-5
lowers HP and Attributes/Attack/Defense (I think?)
No, only the person who pops it can.

Should only need displacers on chair guy in Attowha with a good group,
Can only purchase from the npc for displacers once a per vani conquest.

Bring poison potions for the Apkallu in Uleguerand Range since it spams AoE sleep moves