Do you just simply have to go and kill the mobs that it says to kill? Because I’ve killed probably 1,000 shredders looking for the last two items for the mines level 2 collection, and I can’t find them.
Also do all the collection stats boosts stack? Or do you only pick one at a time?
They are all active at once
You farm the items required and add them to the collection once you have all the items collected the stats activate. There are usually rare materials required in these.
Some items are simply more rare than the others.
For example vubbe fighter blood for crystal mine 3f collection is really rare and drops from a mob that is also not the most common in there. (Vubbe Fighter, the large-type monster that spawns on 3f)
Those that you are missing, I’m actually thinking they might be bugged OR are also quite rare. But considering that they’re just a drop from a regular mob makes me think that the drop rate is a little bugged on those two. I tried to do it this morning too, gave up after killing a bunch. I’ll just buy it later on the AH.
Bonuses stack.
Each completed collection adds a bonus. Those bonuses stack (summed).
…and good luck with those Shredders - they drop those items at very low rate (0.01% probably) so 1k kills is nowhere near enough.
The drop chance is ridiculously low - the first item from Shredders has 0.1% chance of dropping, and the second one is even more rare.
I honestly gave up after 2 hours, I’ll come back to it one day if there is nothing better to do.
If somebody is dumb enough to sell them at reasonable prices…
Yeah, pretty much. 
Are Collection bonuses shared across all characters in a Family/Team? So if I finish two Collection books on my Archer, I won’t have to bother collection materials for those two completed Collection books on a newly made Cleric
they are shared. But you have to activate their bonuses manually by clicking at completed collections at Magic Association NPC for every new character (not sure if it works through F11 menu).
It does not seem to be working for me~ I made a new char to test and it didn’t receive any bonus from the collection~ Could you show us how?
It automatically applies to all of them. If you have complete collections they are applying. My lvl characters hp went from ~200-300 to 600-700
I have completed all items in collection but it is still 0/5. is there any additional step so that the system will recognize my items?
I might be silly here but do you drag and drop the items into the collection UI? That’s how you register the items.