Focus Awards in Fortress Challenges
Each level will award a fixed amount of focus, and it's the same no matter how many foes you must defeat.
The first foe typically grants the highest amount of focus that will be awarded throughout the challenge, and all remaining foes will grant an equal or lesser amount to reach the total for that floor. It obviously doesn't matter what the last foe awards, because you're done with the challenge at that point. I only know what the focus awards are up to Floor 12, so far.
Based on the table above, let's say you're doing a solo challenge on Floor 10. The focus distribution will look something like this:
Floor 10 (Tower V) - 12 Focus
3 Enemies (+4, +4, +4)
4 Enemies (+3, +3, +3, +3)
5 Enemies (+3, +2, +2, +3, +2)
6 Enemies (+2, +2, +2, +2, +2, +2)
This is important because it can help you determine the best strategy to get through a challenge using little or no potion by making the most of your available charms and hexes.
I'm a professor and I've upgraded my initial focus to +4, so I don't have to plan as carefully. If your initial focus is still at +2, understanding focus distribution can be a big deal.
It takes +3 focus to cast the protection charm, which only applies to one player (yourself if you're going solo), and it lasts throughout the floor challenge. Deterioration hex also costs +3 focus, and only applies to one foe. Choosing the right enemies to fight first based on both difficulty and the amount of focus awarded to get the most out of your strategic spells can have a significant impact on the challenge outcome.

Comments
Thank you for your post, great to know!
Also, I noticed when battling together with my wife today, I was able to cast the protection charm again immediately following a single engagement. So, I cast the protection charm on my partner then engage a foe. Once I have defeated him/her and return to the octagon, I then cast it again on myself. Initially I thought I could only cast it once per entire challenge since it lasts for the entire challenge.
I'm still not sure if I had had enough focus, could I have cast the same spell twice before I engaged a foe? If I remember correctly Hexes can only be cast one at a time prior to an engagement (you mention this above). I would think Charms work the same way.
@ZookiTabooki, I believe with enough focus you could go ahead and cast protection charm on both yourself and another player before any engagement, which might be worth doing during a difficult challenge with some help from strong invigoration potion. I don't think you can stack it more than once on a single player, but you can certainly apply it to individual players until you've cast it for everyone in the challenge. It lasts the entire challenge (through all foes) so it's a great one to cast at the beginning. By far, the best charm in the professor's **** is the team proficiency charm, which costs +7 focus, but applies to the entire team and lasts throughout the challenge. It's a great one to break out when you're playing with three or four other people. Generally though, when going solo or with one other person, I start with protection charm and just use deterioration hex on foes after that. If the challenge is only pixies and werewolves, I don't need any help with those as a professor. If I'm battling alongside an auror, I'll cast it on the foes they're fighting, because they have a tough time with curiosities.
I posted a reply @ZookiTabooki, but it appears to have been held for approval, so I don't want to type the whole thing over again only to have it double posted. Short version though is yes, you can cast the protection charm on both you and another player before any engagement with some help from strong invigoration draught. This is because you're applying it to different players, not trying to stack it on a single player. Same with hexes. You can apply deterioration hex more than once before any engagement, but only on different foes. Can't stack it more than once on a single foe.
@Acumen wow! That's a lot of research! Thanks for sharing- i always have to do the ruins solo, great help! Cheers 😊
elite foes always give more focus.
Two questions:
Bumping.
Does this pattern (+1 per floor, first floor of the next group duplicates the last floor of the previous group) continue all the way to chamber 20?
Not sure about pattern over Forest II, but this focus system sucks for Professors cause Deterioration hex costs 3 focus and when there are more enemies focus reward from enemy is not enough for next one.
Seems game dedicated for Aurors only - they !always! have enough focus for both hexes playing solo.
As a professor, I've learned to tell when I can hex them all, and when I need to not hex someone.
And, I'm willing to spend 15 or so seconds as needed to get a choice of who to go after next.
Actually once you get to a higher level it's actually the professors and magizoologists that can solo without too many problems or potions. Aurors on the other hand hit a bit of a cap. We can't heal anything, much less ourselves so it can be a complete loss of a fortress run if we come up across too many spiders, erklings or werewolves (at least in my case). I've had more defeats trying to solo dark chambers just from that 30 second wait period than from anything else, not to mention the number of healing potions I go through.
with essential runestone gifts healing potions not an issue now
professors healing is ridiculous: 4pts every 6 seconds - it is better "to die" and get 397pts after 45 seconds
aurors do biggest damage per time anyway with their enormous critical rate
Sorry, 4 points every 6 seconds is not a lot. One 40 second dirt nap is maybe 6 of those, which would be 24 points. That's nothing.
Aurors do the most damage per time of solos. But they spend the most time down and out.
An auror's bat boogy + a professor's Det is 44 points (?) every 6 seconds, and that's a LOT of damage. One professor and 3 aurors is three times that.
My question: How much can a full party of P + lots of A's take out without ever "fighting"?
Does anyone know when adding charms to players, why sometimes there's a little 'swap' symbol above them? Even though it doesn't actually swap anything?
So this symbol seems to show up in two cases.
One, you are hovering over the foe or player for longer than needed.
Two, you are playing in a group and may be of a higher level than another player who placed the same a hex or charm on the player that you are trying to place.
In the first scenario, the devs (this is buried in one of the forum posts from one of the HPWU team) originally intended that each player could only hex or charm once per foe/teammate. Which meant if you wanted to place proficiency the other professor would need to place shields. This system either never got implemented or was scrapped early on, I don't know which.
In the second scenario, there are two aurors; auror 1 is maxed, auror 2 is lvl 13 and maybe their confusion hex isn't fully fleshed out. A2 puts down a confusion hex on a werewolf. For A1 that confusion hex won't show up until they try and drop their confusion hex on the same wolf. They then get the arrow swap and a pop-up that says that hex is in play but do you want to swap for yours? My guess is this happens for charms with professors as well, but as I am not a professor and haven't opened that tree, someone else will need to confirm.
Hope this helps @Bluebell26