If souls are a requirement at amounts that would make an endgamer even bat an eye, they probably would be fairly cost prohibitive to everyone else, though. I'm getting probably close to 30-50k souls a week without using any soul generating troops at all (above what I need to fully level any new troop that comes along). Before three-star kingdoms or if you don't collect that many tributes, you have to use soul generators just to outpace the release schedule.
In order for it to be something that can be feasibly used by everyone, it needs to scale with both the needs and haves of both end and mid gamers, and it needs to have generate revenue. Mid gamers or casuals are more concerned about unlocking that one copy of an epic or legendary. Most super early gamers don't know what they want yet, but can start establishing some goals within a few weeks. Endgamers want that mythic they missed or another more reliable way to an event legendary, since even those are starting to become less reliable.
A good crafting system should not be both the fastest and easiest way to obtain things either. That is kind of a big problem with the current drop system, aside from the rampant fighting against the tide of ever worsening RNG.
Another consideration is that the only way you can truly make any possible "new crafting resource" able to be reliably monitized, everyone has to be on somewhat of level playing field. If you can just get them from any source already in the game and they aren't hard capped over a period of time, endgamers will get exponentially more of them. No matter what it is. If they are hardcapped at a certain amount, endgamers, who aside from base mythics need a huge number of other troops to ascend to mythic to fill in gaps, would only be using them on mythics - a limited amount and you are done. Neither sounds like a good solution.
A good crafting system would use some kind of time gating mechanism that scales with the needs of the person using the system along with a good amount of something that is readily obtained. Both Souls and traitstones fit the bill for the thing that can be "readily obtained", within a couple weeks even newer players should have some kind of soul generation up and running (or be forever relagated to the casual realm). Souls and traitstones are also both dead-end resources, minors and majors in particular, where you don't even need a great deal of effort to get way more per week than needed to trait any new release and eventually outpace all releases.
Gems are an already monitized, however, this monitization does not scale at all. A beginner buying a gem subscription is paying five bucks for more gems than they could earn in that couple weeks. An endgamer in a semi-casual guild is paying the same gets a roughly 10% bump in the amount of gems they gathered over the same period of time. The beginner gets way more usage out of that 210 gems than the endgamer would get out of all the gems they had earned during that two week period. The endgamer does not buy the gems because not only are they devalued by being abundant versus what can be purchased, but also each individual gem is devalued because you are less likely to get stuff you want when you already have most stuff.
I would propose any crafting system therefore:
- Troops are unavailable for crafting until the week after they are released. Crafting costs for troops introduced within the last several weeks start high, but decrease every week.
- Low rarity troops are crafted with souls and traitstones. High rarity troops (epic +) are crafted with souls, traitstones, and gems. Basically, an effort component and a time (or premium/monetized) component. Either or both components can be new things, but keep in mind that the endgamer is going to need more of them regardless and therefore they need to not be monetized at fixed price.
- The crafting cost of a troop increases on an exponential scale depending on how many troops of that rarity you have crafted that week. The multiplier is more severe for higher rarities (1.05x for common, x2 for legendary, x10 for mythic) and resets weekly (monthly for Mythics).
- If a new resource is introduced in place of using souls/stones, it should be done without artificial hardcaps, for the reasons stated above.
- During a kingdom event, crafting costs are halved. Note that since new troops would not be available that week, this applies to old troops.
- One apocalypse troop is reduced cost (or possibly just available to craft, period) every 3 months. One Imp is reduced cost every two months (preferably the one that dropped six months ago).
Basically, if you want something really quick, you risk it with randoms. If you want something reliably and quick, or a lot of stuff quick, you craft it, but it is going to cost you (either ingame or wallet). If you want just want something reliably but in a reasonable amount of time, you stick it out until it is cheaper/find a balance. If you are playing catch up, you can get really old stuff on the cheap and move up gradually.
The forced wait is the thing that gives me pause here. I really like the "go hunt drops to make troops" as the effort component and I wouldn't mind if that is also what they monetized (sell components to reduce the grind, or just had some gem costs on top of it), but the forced wait also means you can randomly draw the thing you were attempting to craft and therefore would have wasted all the effort (or money) put forth PLUS be locked into that option for so much more time. More than likely given this setup, they'd also likely monetize to reduce the wait, making crafting just slightly less of a risk to use if and only if you pay, which is kinda what they need to get away from with a crafting system. There are a lot of things I'll pay for, but at this point, I'm not putting any more money down just to wrestle with RNG.