I'm wondering if the current casting cost of Spell of Mastery is high enough, considering the high amount of skill a player typically has in the endgame now.
While the cost is double of the original, skill is also double most of the time, often even triple.
I had a game where I finished by casting SoM yesterday. It took me only about 21 turns to cast it despite not spending at all on casting skill for the second half of the game and not having AEther Binding. Now, 21 turns without casting other overland spells is a lot. Yet, it's very small considering the AI has to actually take out your capital in that time, just taking cities, even if you lose 90% of them, will not do anything.
I've implemented an elevated hostility system so the AI can at least be more aggressive and send in units to the capital even if they would normally think "this is too well defended to attack with just 5 Sky Drakes" , hoping to slowly wear it down by combat spells, because waiting for a stack that is better than the 9 best units the player has at this point is unrealistic, especially if it contains all 6 of their heroes. However that isn't the only thing preventing the AI from taking the player out :
1. Diplomacy. The number of turns are random but it can take anywhere from none to as much as 5-6 turns before the AI starts the war, until then they just keep warning you about breaking the alliance. (this doesn't apply if there was no alliance, then they attack right away) This is an insignificant amount of time or would be if the spell took longer to cast.
2. Logistics and distance. While the new AI will give up committing stronger forces on defense in this situation and will use all they have to form attacking armies, it takes quite a few turns to gather them on one spot, ferry them across the ocean somehow, then make their way into the capital.
3. Other cities. Even if the capital is the highest priority for an attack, the AI has multiple armies and they will target other cities simultaneously. If they manage to conquer them, some of them will be stuck inside as garrisons. There is also no guarantee the strongest army will go to the capital, in fact as it is now allowed to attack it with anything to prevent not attacking at all, chances are it will be medicore or even outright weak. Distance also isn't a factor, while the priority of targets is weighted by it the capital has a large priority so a unit going there from the other end of the continent is possible...and if they do so, nothing else will attack the capital until they reach it, except for stacks that are no further than 5 tiles. (maybe the "no secondary attack force for a target unless it is at a distance of 5 or less" condition should be removed? I suppose if a unit had nothing else to attack then...actually no. That would mean everything moves towards a weak target if one is found, leaving the stackbuilding and garrison refilling modules with no units left to choose from. So that shouldn't be done.)
4. Move Fortress. The human player will have their fortress at a place that is hard to reach. If the map allows they might even put it on a 1 tile island where only flying stacks can enter, which do not use the normal target priority system and will not be able to bypass the "too strong to attack" limitation.
So yeah...should it cost more or not? Even if it did, the AI's chances to stop it through military force are marginal but as is, it's zero.
Of course we can also say if you got the spell first and made sure no one remaining has Spell Blast then you deserve to win and ignore this as a non-problem. Many other 4X games just declare "X wins by <condition>" without letting anyone use force to stop it ; at that point, it's just a game over screen. They should have attacked while it was being researched, there was plenty of time. (except they can't do that if there is a stable alliance...)
Another thing, the human player can push their research bar to the max. The AI cannot and even with their power advantage, if they only spend a third on research while you spend the full, you will be faster (also the AI pays 50% more for researching SoM on extreme and higher, otherwise games would end too early to enjoy). On the other hand the AI shouldn't be allowed to max research intentionally to win unless we want to see games where "oh cool I have some very rare spells now, let's start summoning and prepare a plan to deal with the enemy....hey don't win the game when I haven't even used my best spells yet, where is the fun in that!" happens. They have a low research advantage to prevent this, but their power advantage is big and they can have very large empires, often two or three times the size of the human player. If they could push all that 3-5k power/turn into research they'd finish researching it in just 50 turns.
Finally there is the other side to this. The player also needs time to gather troops, get to the AI's capital and defeat what is inside. If they only have 15 turns for the whole thing, that might not be enough, especially if they need simultaneous attacks with multiple stacks to do so.
...it's worth mentioning I don't normally win by SoM, this was the first time in a long while. I had too few books (used random generator) and had no means to take out the capitals, aside from risking an all out attack with my heroes, which is just too risky when said capitals are full of Great Wyrms, colossus and both remaining wizards have web+crack's call and disintegrate and chaos books to go with it. Now that the AI knows what Spell Save items are, and prefers to equip it on their top hero, walking into a capital using heroes with "only" 15ish resistance is no longer safe. If the hero is the illusionist, it can take out 2-3 heroes with disintegrate on turn 1. I would have tried if there was no other way but conveniently no one had spell blast and I had a resource advantage so I went for it. SoM needed testing anyway, looks like it's viable on extreme if having a large enough power advantage.
Edit : I checked my save file. At the time I won, one of the wizards still had 30k left on their SoM research, the other had 45k and two unresearched very rares (probably from books). The latter is of no concern, they were behind me in power the whole game and playing Dwarves (although they had Sage Master). The former was Theurgist and had cities of all sorts of (arcanus) races, started with barbarians, but also had only half my power for most of the game (I took away about half their cities, that's why). I guess these numbers are reasonable, I feel the AI was a bit lagging behind research but it's only extreme not impossible and the conditions were far from ideal for them (fully or partially low research races and limited space for expansion - I colonized or conquered about 60% of Myrror so my ally only had 40%, and on Arcanus I took the cities from the player there so by the time they could have had good research from nonbarbarian cities, they started losing them one at a time). I finished casting SoM in 1425 which is surprisingly early for that but I was playing Dark Elves on high (maybe even max?) power settings.
While the cost is double of the original, skill is also double most of the time, often even triple.
I had a game where I finished by casting SoM yesterday. It took me only about 21 turns to cast it despite not spending at all on casting skill for the second half of the game and not having AEther Binding. Now, 21 turns without casting other overland spells is a lot. Yet, it's very small considering the AI has to actually take out your capital in that time, just taking cities, even if you lose 90% of them, will not do anything.
I've implemented an elevated hostility system so the AI can at least be more aggressive and send in units to the capital even if they would normally think "this is too well defended to attack with just 5 Sky Drakes" , hoping to slowly wear it down by combat spells, because waiting for a stack that is better than the 9 best units the player has at this point is unrealistic, especially if it contains all 6 of their heroes. However that isn't the only thing preventing the AI from taking the player out :
1. Diplomacy. The number of turns are random but it can take anywhere from none to as much as 5-6 turns before the AI starts the war, until then they just keep warning you about breaking the alliance. (this doesn't apply if there was no alliance, then they attack right away) This is an insignificant amount of time or would be if the spell took longer to cast.
2. Logistics and distance. While the new AI will give up committing stronger forces on defense in this situation and will use all they have to form attacking armies, it takes quite a few turns to gather them on one spot, ferry them across the ocean somehow, then make their way into the capital.
3. Other cities. Even if the capital is the highest priority for an attack, the AI has multiple armies and they will target other cities simultaneously. If they manage to conquer them, some of them will be stuck inside as garrisons. There is also no guarantee the strongest army will go to the capital, in fact as it is now allowed to attack it with anything to prevent not attacking at all, chances are it will be medicore or even outright weak. Distance also isn't a factor, while the priority of targets is weighted by it the capital has a large priority so a unit going there from the other end of the continent is possible...and if they do so, nothing else will attack the capital until they reach it, except for stacks that are no further than 5 tiles. (maybe the "no secondary attack force for a target unless it is at a distance of 5 or less" condition should be removed? I suppose if a unit had nothing else to attack then...actually no. That would mean everything moves towards a weak target if one is found, leaving the stackbuilding and garrison refilling modules with no units left to choose from. So that shouldn't be done.)
4. Move Fortress. The human player will have their fortress at a place that is hard to reach. If the map allows they might even put it on a 1 tile island where only flying stacks can enter, which do not use the normal target priority system and will not be able to bypass the "too strong to attack" limitation.
So yeah...should it cost more or not? Even if it did, the AI's chances to stop it through military force are marginal but as is, it's zero.
Of course we can also say if you got the spell first and made sure no one remaining has Spell Blast then you deserve to win and ignore this as a non-problem. Many other 4X games just declare "X wins by <condition>" without letting anyone use force to stop it ; at that point, it's just a game over screen. They should have attacked while it was being researched, there was plenty of time. (except they can't do that if there is a stable alliance...)
Another thing, the human player can push their research bar to the max. The AI cannot and even with their power advantage, if they only spend a third on research while you spend the full, you will be faster (also the AI pays 50% more for researching SoM on extreme and higher, otherwise games would end too early to enjoy). On the other hand the AI shouldn't be allowed to max research intentionally to win unless we want to see games where "oh cool I have some very rare spells now, let's start summoning and prepare a plan to deal with the enemy....hey don't win the game when I haven't even used my best spells yet, where is the fun in that!" happens. They have a low research advantage to prevent this, but their power advantage is big and they can have very large empires, often two or three times the size of the human player. If they could push all that 3-5k power/turn into research they'd finish researching it in just 50 turns.
Finally there is the other side to this. The player also needs time to gather troops, get to the AI's capital and defeat what is inside. If they only have 15 turns for the whole thing, that might not be enough, especially if they need simultaneous attacks with multiple stacks to do so.
...it's worth mentioning I don't normally win by SoM, this was the first time in a long while. I had too few books (used random generator) and had no means to take out the capitals, aside from risking an all out attack with my heroes, which is just too risky when said capitals are full of Great Wyrms, colossus and both remaining wizards have web+crack's call and disintegrate and chaos books to go with it. Now that the AI knows what Spell Save items are, and prefers to equip it on their top hero, walking into a capital using heroes with "only" 15ish resistance is no longer safe. If the hero is the illusionist, it can take out 2-3 heroes with disintegrate on turn 1. I would have tried if there was no other way but conveniently no one had spell blast and I had a resource advantage so I went for it. SoM needed testing anyway, looks like it's viable on extreme if having a large enough power advantage.
Edit : I checked my save file. At the time I won, one of the wizards still had 30k left on their SoM research, the other had 45k and two unresearched very rares (probably from books). The latter is of no concern, they were behind me in power the whole game and playing Dwarves (although they had Sage Master). The former was Theurgist and had cities of all sorts of (arcanus) races, started with barbarians, but also had only half my power for most of the game (I took away about half their cities, that's why). I guess these numbers are reasonable, I feel the AI was a bit lagging behind research but it's only extreme not impossible and the conditions were far from ideal for them (fully or partially low research races and limited space for expansion - I colonized or conquered about 60% of Myrror so my ally only had 40%, and on Arcanus I took the cities from the player there so by the time they could have had good research from nonbarbarian cities, they started losing them one at a time). I finished casting SoM in 1425 which is surprisingly early for that but I was playing Dark Elves on high (maybe even max?) power settings.
