So I've determined that theoretically speaking, the path of war map without the sslaks or the orbs is likely to be ideally suited or almost ideally suited for regular 1v1 arena play.
I did that by measuring the transformations from the regular 3x4 arena to path of war without the sslaks. I used increase/decrease in #of zones as the unit, and I approximately converted every change between the two maps into said unit.
1. For the most part secret passages come in groups of 2 or more. If they're at range 1 from each other, then the change from the 3x4 map is 0. If they're at range 2 from each other, the change from the 3x4 map is -1. The secret passages on the path of war map are at range 4, which means that secret passages on the path of war map are a change of -3 from the regular arena. Well they would be, if they didn't block line of sight and things could be teleported or pushed through. So it's actually slightly more than -3. For now we'll assign it a value of ~-2.5.
2. the distance between starting zones is 5 in the regular arena. In path of war, the distance is 6 (not counting the secret passages). Therefore the change from the regular arena due to the distance between starting zones is +1.
3. Corrosive pool/Molten rock hinders non-flying corporeal creatures, including mages. Each of them is +1. Or it would be, if they only hindered and did nothing else, and was positioned to affect both sides equally. But they also can cause some damage through their burns/corrodes. So let's assign each corrosive pool and each molten rock a value of ~0.5. one one side of the board, and if there is another one in an equivalent position on the other side, give it the opposite sign.
-2.5 +1 +0.5 -0.5=-1.5
If a map has a negative value, that means that it will tend to have shorter 1v1 games than the regular 3x4 arena.
Sslaks hinder too. If you add four sslaks, that's approximately +4.
-1.5 +4=+2.5
sslaks take ~2 attack actions to destroy. Then it takes a third attack action to attack an orb. So if you add the domination victory condition, it should be an increase of ~+3 per sslak. It's actually a little bit more than this because of the mana and healing bonuses from the v'tar orbs. With a win condition of 11 v'tar, that means you will have gained 13 mana/lost 13 damage/some combination by the end of the game, IF you win. Since you have ~3 quick actions and 19-20 mana at the start of the game, we'll use that as the baseline, so +13 mana by the end of the game, so you've gained approximately the equivalent of somewhere between 6 and 7 quick actions.
We'll take the average of that (since all mages start with either 9 or 10 channeling), so the domination win condition + the sslaks is +6.5 +12= +18.5, but ONLY if you win by domination victory and your opponent never uses an action to damage any sslaks. If a player wins by killing the mage, that would lower the increase in the map value by the amount of v'tar needed for the player leading in v'tar to win by domination, divided by 6.5 (the average amount of mana per approximate quick action at the start of the game).
So 18.5 -((v'tar left to win when a mage dies)/6.5)=~the change from the regular game by adding 4 sslaks, 4 v'tar orbs, and the domination victory condition.
So if 18.5 -((v'tar left to win when a mage dies)/6.5) -1.5 = ~0, then the path of war map in domination 1v1 play would be pretty much perfectly balanced.
In other words, on average, the value of (v'tar left to win when a mage dies) is how much v'tar the enemy mage should have at most by the time you kill their mage, if you want to win by killing their mage. This is still of course an average theoretical value, and it is quite likely to be off.
Something else to keep in mind is that what I've been measuring so far is difference in balance between both sides of the map. There is a second type of map balance involved in balancing early game with late game playstyles. For instance, Putting 2 Ethereal Mists in corresponding locations on both sides of the map will benefit all playstyles, but more defensive/longer game ones will benefit at least slightly more. However, in terms of the overall power levels of each side of the map, there's no difference at all. Ethereal Mist increases the number of move actions needed to cast spells on an object in its zone by 1. (Melee attacks already can only be at range 0 regardless.) So if you put 2 ethereal mists in corresponding positions on opposite sides of the board, longer game/more defensive strategies will benefit equally on both sides, and more aggressive/early game strategies will benefit equally on both sides, but the longer game/more defensive will benefit more on each side than the shorter game/more aggressive.
In addition, this system isn't perfectly precise. Because of all the approximations, sometimes the maps you make using this method will not be quite as balanced as they should be. Playtesting should give you a general sense of where the errors are, and might even help you be more precise in how you assign value to different map features.
I'm particularly interested in whether Ethereal Mist generally has a higher or lower value than septagram when septagram isn't able to protect mages. When it is able to it's almost certainly more, likely at +1.5, since the only way to cast a spell on an enemy mage that's protected by a septagram is to either wait for them to move out of it, or use a nonspell effect to get them out first, (probably a +1 if you're lucky, +2 or more if you're not) but you can still melee attack them or ranged attack them just fine, so that would be a change of 0. Take the average, (2+0)/2 =1 or (1+0)/2=.5.
Obviously there's still a lot of approximation involved here. ALWAYS playtest if you're unsure how balanced your custom maps are. All this math is only going to get you an approximate theoretical value for map balance. If you really want to know how balanced a map is, try it out for yourself. Overtime, as you make and test more and more maps, the mechanics of map design likely will become more intuitive to you. You might start to get a sense for whether a map is likely to work, or whether something is wrong with it.
