When are the multipliers applied, during the challenge, or after the challenge is all over?

Interesting... I like the idea your coalition mates will multiply your own rewards...

@Zarakthusma : it's a bit unclear right now, but it looks like they're the standard, individual rewards that are displayed. Let's hope we'll get twice this ! ;)

Zarakthusma, multiplier is applied to your personal rewards after the challenge is over. 

im not exactly sure on how to follow/understand  the rewards/requirements etc?

for example the icon for the mystery chests - 

In the first Column The description says 

2/6   
  "Go to the CACHE Tab of you Sanctum of Asclepius to extract the elixir"

           2  

The second column says 

+1                      +1             +1                   

     39/400     <>750      <>2500            Remaining 4

so what exactly does it mean? 

does the 2/6 mean that i have opened 2 elixirs of 6 required to get a reward - im guessing the number 2 under the icon is the amount i get as reward???
does the 39/400 mean ive extracted 1 elixirs 39 times already and need to extract another 361 elixirs to change the first numbers to 3/6 and then have to repeat it again 1200 elixirs to make it complete or are soem of these numbers affected by coallition members etc 

please please explain as i really dont understand what i am required to do in order to get rewards etc. this applies to all of the rewards btw, just used the elixirs one as example ( i have been to my cache and activated and then extracted my elixirs time after time and none of thesee figures in the chart have changed - even after relogging - so please please please explain it a lot more clearer for people like me who just dont get it thank you so very much

 I believe its like this.....

the 2/6 above the icon means you are currently in the tier 2 prize range  of an available 6 tiers
The icon  - the description is of the reward - not of its requirements- (so the reward is mysterious chest that can be opened by visiting the cache etc)

the #2 under the icon represents how many of the item you are in line to receive - so in this case its 2x mystery chests.

the +1 represents the next tier and how many contribution points more are needed between the current tier and the next - so in this case ( 39/400)you need to earn 361 more contribution points on top of what you already have in order to now be in Tier 3 rather than tier 2 for this particular reward.

but I think this second column may also be affected by your coalitions input also - would need some further clarification as tp the mechanics fo rthis though.

So the long story made  short  - The left column is the rewards  you are already in line to receive.

just keep on trying to  earn more contribution points and get better rewards - if you are in a coalition then encourage them to do the same for some bonus rewards - simples!!!!