New experimental version

[Nelphine]

I don't think we should be aiming to allow time stop spell of mastery. Givng you a few rounds sure, but not a complete cast. Personally i think the story of how it's going in your game is ideal. It should be good, not an auto win. You should have to think 'do I cast time stop or do I do something else?'. And personally from what you are saying its STILL 'always cast time stop' full stop. Which means the price should certainly not be reduced, without many more games to test it. If I had to guess, I'd say its still too cheap.

[Nelphine]

Actually, one thing about time stop and casting skill. Amp towers are huge for end game casting skill. On large, I would fully expect a sorcery wizard to have 500 (or more!) Casting skill. But on tiny or small you might not.

So, cost should be (75+5/land size)/turn.

So huge would be 100, tiny would be 80.

[coldsteel]

It seems like water elementals are far better than anything else comparable and along with aether binding make sorcery AIs the toughest opponents in general.

[Seravy]

It seems like water elementals are far better than anything else comparable and along with aether binding make sorcery AIs the toughest opponents in general.

There are only two other uncommon ranged summoned units in the game.

Fire Giant costs 40 less, is overall somewhat weaker but has Fireball Spell which makes it work better against multifigure enemies than the Water Elemental. Overall I'd say they are equal maybe slightly worse because they don't have waterwalking.
Shadow Demons cost 25 more, their damage output is probably similar, but come with twice the ammo, flight, regeneration and plane shifting. They are definitely much better.

Time Stop : looked at my tables again. At the current amount, assuming 20k mana spent at one go (I think that's a bit of an overestimation for human player uses, nowadays it's not that trivial to save up that much with Amp Towers costing 20/turn and more troops necessary in garrisons also driving up maintenance costs) you need 300 skill to "break even", below that you're actually losing casting opportunity (but get it all at once instead of over the course of the next 100 turns). 
At this number, you can summon 10 very rare creatures from spending 20k mana. That sounds impressive and intimidating but...there is a catch. They aren't all that expensive anymore. So you're spending 4 turns (to cast Time Stop itself) on getting 10 of them - with 300 skill you'd otherwise need 17 turns. So you get your stack of Sky Drakes 13 turns earlier.
That's impressive. But not impressive enough to burn 15k mana crystals I think. For that, I could cast Flame Strike over 200 times in battles! So yes, compared to burning that 15k on raising casting skill, where I'd get said additional Sky Drakes in 100 turns and after that the gained skill is still there to use, getting it immediately is much better but this just shows how bad burning mana on skill once it's already high is. Actually it's not, we didn't consider Amps in the calculations. Big mistake. If half the 300 skill is from the towers, then it only costs 1/4 as much to raise skill so...might as well redo the whole thing now....
Give me a few minutes to recalculate.

[Seravy]

   
So this is the correct table, recalculated. I changed mana used per go to 15k as it feels more reasonable for a human player. I tested various values but using larger or smaller chunks in one go doesn't seem to alter the break-even point significantly, thanks to having to recast the spell so it doesn't make much difference either way.

What does make a difference is, I changed the cost of gaining 1 skill to S instead of 2*S to account for half the skill being from Amplifying Towers which does not raise the SP cost of raising the skill.

If we want this to "break even" at 250 skill, we'll need a cost of 30 MP, omg.
That still means burning 15k mana on 13 Sky Drakes which would otherwise only cost 6500 so it's a sacrifice of 8500 mana to get them 20 turns earlier. I think that sounds a good deal unlike the 15k wasted for 10 of them 17 turns earlier...but it's still not a trivial decision, if you can afford waiting out the 20 turns and need that mana for combat spells, not stopping time can work better. In fact, summoning first, then stopping time and not casting overland spells to ensure you can commit as much as possible to combat spending to support those drakes might be a better tactic.


At that cost, it takes roughly 13 turns before the new spell gets more expensive total than the old 200/turn. After that the total cost gets more and more off the chart and ~40 turns is probably the most you can get out of the spell even if you burn through a full 30k mp and gold.

Interesting to see even if you have twice as much skill, you aren't getting twice as many drakes, because at that point the cost of summoning itself is a large enough chunk to start outweighing the maintenance of Time Stop.

And the really interesting thing is, cutting the price to 30 from 100 didn't increase the number of turns all that much. I was expecting 3 times as many turns but it's only ~50% more.

So...unless someone can point at a flaw in the above table/calculation, I'll modify the cost to cumulative 30/turn?

[Nelphine]

Why is 15k reasonable? Oh. I always play alchemy. That makes a huge difference. Hmm. I'll have to readjust my thinking. (My life games, aside from the first 3 turns if a war, I can quite literally be capping both gold and mana.)

I also firmly think it should be higher than 250 break even. I generally have 200 cadting skill, without amp towers, by the time very rares matter. (And not counting spellweaver or heroes).

At the very least the break even should be 300 (that's 25% less than me, plus amp towers).

I'd also rather it start higher. Even a few turns can be massive from an overland combat point of view (effectively stasis on every enemy stack).

So, something like 60 +40/turn (so turn 1 starts at 100).

I also think land size really should be included in the formula, as you'll have a HUGE variety in number of amp towers.

So 60 + (25+4/land size)/turn.

[Nelphine]

Did you see my last hydra post?

[Seravy]

Yes. And I don't see how you killing Hydras is relevant to the human player using Hydras. Hydras are fire breathing and low armor - if you surround them with many smaller units and attack, of course you'll win (although it eats half your halberdiers). But try that against 9 Hydras moved by a human player.
Also, out-of-realm spells are supposed to be somewhat weaker than other spells in the same rarity but with a matching realm. A regenerating, high health Chaos monster is definitely out-of-realm. So it should be weaker than a Behemoth. It's attack power and health is definitely stronger, so that leaves the movement speed, armor and resistance to compensate for both.

9 Swordsmen might allow you to cast combat spells - but they won't survive to do it every turn, nor will they work against 9 Magicians or anything better. Hydras can laugh at 9 Storm Giants while you Flame Strike all 9 to death, albeit you obviously need more than 1 hydra for that, probably around 5. No cheap normal unit is going to do that for you.

[Seravy]

About land size : More amp towers definitely give a large variance in skill, but that translates into less variance in profitability, if you look at the table. Also, the whole point of Amp Towers is to grant additional casting skill on larger maps, and time stop skill shouldn't be an exception to that. What's worse, the MP cost has a way lower influence than the skill so it's not easy to compensate through that.
Initial cost : makes no sense and it's meaningless. First, it's paid in all turns not just the first so ultimately it just makes the spell more expensive in a linear way, not in the early turns specifically - so it puts the formula halfway between the original and the current. Also, there is a huge initial cost : You have to cast it for 1500 skill and mana, so you need at least 3-5 turns just to get that invested skill back (and then you're still very negative on MP without any gains whatsoever on skill, let alone reaching the break even point when the gained skill is worth as much as the lost MP.)

As I said, 15k or 20k or even 30k mana makes no real difference in the break even points, surprisingly.
The most expensive parts of Time Stop are the initial investment and the final turns, the most profitable are the early turns. Spending more MP increases the amount of final turns, so while it offsets the even greater initial investment, it's much worse than the medium turns. In the ends, two 15k Time Stops and a 30k Time Stop end up similarly efficient.

PS : Note that "break even" does not mean profitable. It merely means it's not making a loss (in used up resources VS dumping all of them into SP). So if the break even is 300, you'll need like 400+ skill to actually care about using it to gain additional casting ability. (you might still want it for military/ movement purposes but that's a different story) Also, while it means it's not a loss compared to getting SP doesn't mean it's worth it. Often it's better to spend it on RP or use the mana crystals on combat spells, so even if Time Stop is the best option for producing skill, you still need to decide if you want that, or want mana/research as those might contribute to your strategy better than "hey I have another 9 <insert creature name here>!". Very much like how you don't always want to max the SP slider, often you want RP or MP instead. Time Stop only allows you to get more out of the "SP slider" through producing MP instead and casting it.

...I'm starting to think all of this casting skill calculation is just the "icing" when Time Stop literally allows you to clear the entire map using your best doomstack instantly. Or allows you to fight enemies with 0 MP because they can't refill their reserves during it. In other words, it just wins the game, extra skill or not. And you don't even need many extra turns for either of those.

[Nelphine]

The last comment I agree with on time stop. Its the main reason I think cumulative 100/turn is probably too low. But you wanted to base it on the casting skill, so I tried to go with that.

Hydras - I'm not beating 1 hydra with halberdiers. I'm beating 5 or 6.

You have yet to show any problem with hydras being too strong that isn't a) strategic combat (which is messed up with multi figures, and hydra have the most figures in the game -of course they'll have high strategic strength. Trying to fix that without fixing multifigures in strategic combat is a mistake) or with mystic surge (which has never been fully tested, I've considered overpowered since the start, and the combination of mystic surge and hydras was specifically brought up when mystic surge was introduced, and you specifally liked the potential combination.)

Neither reason is a reason to weaken what is arguably the weakest very rare unit in the game.