Coal, Steel, camouflages, ships from Directives, containers with a chance of dropping Premium ships, a new collection, and much more! Read on for a complete overview and instructions!
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I don't have the relevant patch yet, so I'm just assuming you'll have to do the vast majorities of missions to the point where you'll have to do nigh all of them. IF you require only a few missions per stage AND IF you can then combine several targets into fewer games, then you'll be able to get there faster.
Looking at the requirements of the missions, ie ~800.000 base XP, 1.400.000 free XP I'd guesstimate that with an average of 2.000 base XP per battle and 20.000 free XP, this already means you'll have to play 470 games. Add in additional games for some ribbons you need to finish, extra credits you need to earn or inviting the enemy team to shoot you some more, I'd put that number at 600 games at a bare minimum.
You've got 28 days for PR, 33 for all directives, which means you'll be playing 21,5 games per day. At 15 minutes per game that's about 5 hrs and ~20 minutes playing WoWs per day, every day.
If you don't score an average of 2k base XP, it'll take longer:
(compared to 2k base)
1900 average base XP: 421 battles
1800 average base XP: 444 battles
1700 average base XP: 470 battles
1600 average base XP: 500 battles
1500 average base XP: 533 battles
And that's just the base XP grind, if you usually score less, the Free XP grind at stage 7 will also take longer and we're closer to the realm of 700-800 or more games. At 800 games in 28 days, you're looking forward to about 7 hrs and 10 minutes of straight up warships.
However, if you generally avoid playing random battles and confine yourself to coop, well... I'd argue that it's flat out impossible for any single human being to grind this in Coop only.