All of these effects are multiplicative, and not additive. Therefore, it would be the latter case.

Why am I not getting credit for 10 simultaneous debuffs on fire knight at stage 12?

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Because you have 6 debuffs up, not 10. Has to be 10 at the same time. There needs to be 10 debuff icons. 

Thanks, I wasn't aware that it was based on icons. I guess I won't be doing this quest any time soon.

Might be possible, still. Can you find a way to jam more poisons? 

Hello and happy new year.

Im wondering (for clan quest) how to put 5 or 10 simultaenous debuffs on a dungeon boss. 

Meaning, to put them on the same turn, before he starts his attack?

It is determined by the skill rotation of the champs. The skills list what debuffs they can land and any restrictions or prequisites, if any.

When the skill procs a debuff AND they make their Accuracy versuses the target's Resistance it hits. Just a matter of having enough champs, throwing enough debuffs and enough Accuracy to ensure landing.

Yes, it means all 10 debuffs must show the debuff bar at once, simultaneously

As a relatively new player [11 months ftp] I struggle to work out what is required sometimes as it is not explicit on the page - and it can get tiring looking for exact answers even here and in reddit. However, I succeed for the first time today in placing 10 simultaneous debuffs on the Spider Boss at stage 10 after trial and error and was awarded 200 Expert Clan points. I used Kael; Geomancer; Scyl; Coldheart and Frozen Banshee (2 books shy of beign fully booked and in Retaliation and Divine Speed Gear  - tho' none is levelled up; she is the only one at level 40; the rest are at level 60). I had 10 debuff boxes lined up when I used  another champion (Artak) in place of FB but it did not count for some reason unknown to me.

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