I've already commented my opinion below but I also would like to know what these "serious implications for the overall game economy" are?
The $10 spellbook kind of helps prohibit immediate profits. On average every account created would take 1-2 weeks before even making back the spellbook cost. Then for each account they're maybe making an average of $1 a day?
I realize there could be bots playing the accounts, but they still have to win 5 games a day as well and bots generally suck, so they may not even be able to do that. And if bots are the concern, you are trying to cure a problem with the wrong cure here.
But otherwise manually playing accounts I can't imagine a person doing more than a dozen or so. Given this is a play to earn game, paying $10 to eventually start earning about $1 day for 30 minutes to an hour of play per account does not exactly seem economy breaking. The amount of time it takes to win 5 games will also go up as the account ranks up, making it even more difficult and take longer unless they're also renting/buying cards. In which case that dollar a day profit is gone and the overall economy is actually benefiting from the extra accounts, not suffering.
And if you are talking about DEC. With the airdrop, the influx of players, the increase in cost of basically everything, there is virtually no reason players would be dumping DEC right now. The cost will most likely just keep increasing. This move will likely help it continue even faster given the amount of DEC being cut off from players that didn't have quest potions saved up right now.
So what exactly is the disruption in the game economy that warranted this immediate change?
As far as I can tell the only things this is going to accomplish is 1. Make new players angry (which can be seen by the amount of comments here.) 2. Cost you money as people completely stop buying potions (and no doubt some people quit playing the game completely and by extension do not recommend it to friends.) 3. Slightly slow down the issuance of DEC but probably have no real impact on the price action because slower issuance is not the same as burning.
The ONLY thing I can think of is that the slight increase to DEC rewards coupled with the massive influx of new players is making the SPS airdrop run out faster than expected? If that is the case, this is probably not going to be enough to stop that.
Again, not trying to be negative here. Just hoping for a bit more information and maybe a better solution to whatever problem is trying to be solved here.