Voidwatch is split in 3 path: cities, jeuno, zilart. You can partecipate to any fight and get reward even if you have or not the stratum abyssite upgraded for that path.
the only thing needed is one voidstone for each fight you'll do to gain reward as item otherwise you can even partecipate to the fight and get reward but only as exp/cruor.

every VWNM has 6 tier weakness to proc; you can find almost all weaknes found on this page:link text

Those are splitted into NQ(1); HQ(3); EQ(5) and those are 3 types MAGIC proc or red ( raises quality reward ), JA(2)/WS or blue ( gives more quantity reward )
-NQ stagger effect:will stagger for 5 seconds and can give back 1 temp item used. Usually it's the last one you've used
-HQ stagger effect: will stagger for 20 seconds and it give back all temps item.
-EQ stagger effect: will stagger for 30 seconds and it give back all temp item plus it cap all light.
Alignment is calculated in the order shown in the table below.



to know:
Rubicond cells help to raises final reward quality
Cobalt cells help to raise final reward quantity
TH does work in this way:
Alignment gained from Treasure Hunter is a percentage equal to the TH level, multiplied with the total alignments (including that from ascent items) at the end of the battle before applying bonus alignment from periapts (e.g. TH6 will add 6% to the previous alignments, 200% -> 212%). However, Treasure Hunter cannot make alignments exceed 300% for green/yellow or 500% for red/blue prior to periapt bonus alignment.

if you ran out of void stone you can get more trading voiddust to voidwatch officer; 1 up to 4 at same time.