If you have an artifact and an advancement that add 100% to say army camp production, do you get 3 or 4 times the initial output.
For that matter how do those 30% bonuses you get from finishing maps quickly combine with the artifacts and advancements.

Bonuses combine additively.

Discounts combine multiplicatively.

The math works in the way thats worst for the player:

If it increases, it adds

If it discounts, it multiplies


In your example :
base_income * (100% base + 100% advancement + 100% artifact + 30% reward) => 3,3 times the base output

So the supercharge army camp and army camp boost artifacts become more meh over time if you increase the army camp advancement.

SAC multiplies by 20 always

So the supercharge army camp and army camp boost artifacts become more meh over time if you increase the army camp advancement.

SAC is still good, but yea Artifact dilutes a bit.

Let's say Army camp Adv @ 100%, then adding Leg Army camp boost Arti @ 160% will over double the benefit from 100%->260% (2.6x benefit).

But when you get Army camp Adv @ 500%, then adding Leg Army camp boost Arti @ 160% will only increase to 660% = +32%, so not a big deal.

However SAC will always be 20x (multiple) of a single army camp after both Adv & arti buffs have been applied.

Good to know, if I get Army Camp Boost I won't focus on pumping it too much compared to others.

The ad-reward in the mobile app similarly applies in full percentage all the time, just like supercharging. Don't know why, to be honest, but why complain. So, all the "usual" army camp production boosts apply additive, but then Supercharging is a simple 20x and the reward for watching an ad is another simple 20% (or 30% with the reward for the hardened level) on top, no matter the underlying boosts. So, if all the other boosts combine to an overall army production from one camp of say 20k, and you have both a supercharge and an ad-reward on this army camp, your camp will produce 480k (or 520k) (20k x 20 x 1.2 (or 1.3)) for the duration of both boosts applying.

Good to know, if I get Army Camp Boost I won't focus on pumping it too much compared to others.

I wouldn't generalize this way. Because you are correct that you have diminishing returns when you have several boosts for one income and they combine to your disadvantage (sort of), but there is a lot that is calculated based on army income, so, you really shouldn't skip boosting your army income JUST BECAUSE the effects aren't that great. The number of armies that you draft is dependent on your army income. The amount of FC armies depends on your army income. The size of clan requests depends on army income. And perhaps I might even have missed one thing here. So, having a higher army camp production is never a bad thing. And will always account for more than just x armies more per second.

Edited 7/8/2022 23:04:58

Good to know, if I get Army Camp Boost I won't focus on pumping it too much compared to others.

I did the same, not upgrade it too much b/c compared of phase 1 Adv, it's small.

Until you SAsc, after which you'll likely never upgrade IACP to 500% ever again, and then suddenly the AcampB arti becomes useful again to maximize Mobile bonus + arti + SAC+FC effects for starting levels. And clan reqs. Useful b/c you're really just racing towards Hex to get 134K AP & SAsc again w/o investing in much of anything, as little as possible.

So useful-ish when you first star the game, fairly useless once you get strong (a few Asc's), then useful post SAsc.