I can’t find anything concrete on what makes the mission cost fluctuate. Some missions cost more than others- the highest I’ve seen so far is 52 anima- but I can’t figure out why. I’m not even paying to heal followers, and it seems like I’m wasting my time with this part of the game based on anima spent vs anima received.
Every mission has a base cost, and then every minion you put on the team adds 1 anima.
So theoretically if you can finish them with just heroes then they’re more efficient, but when you’re getting down to single digit anima it’s not really that impactful.
As far as why the base costs are what they are, I have no idea. Some of the XP token ones are 50 and some are 150, and with no discernable difference in reward. I just ignore the 150 ones.
The anima spent / anima gained ratio isn’t that great until you get your sanctum fully ranked up, as the anima increase from that applies to mission rewards too.
If you’re just trying to not lose anima, focus on the anima and gold missions. Those are almost always the lowest base cost.
The difficulty rating of missions also impacts the base cost although it has a big range.
Typically the standard missions have a base cost of 10, those usually reward gold or anima.
Then you have “elite”(silver dragon) missions for 30 anima, and “rare elite”(gold dragon) missions for 50 anima.
Sometimes, usually after finishing all the campaign missions, you will get ones that cost even more anima and usually offer things like soul ash, soul cinders and a few other things. I think 150 or 200 is the highest they might cost.
Adding minions increases the cost by 1 per minion also, as Briselody mentioned.
Keep in mind the “difficulty” of missions means almost nothing outside of anima cost. Some of the normal missions are impossible to beat without an ideal setup of troops and companions.