Personally, I’d prefer to see troops being made purchasable with extra souls, at a rate of 1000x disenchant value.
Want a common? that is 5 x 1000 = 5000 souls each. Completely impractical, but an option.
Need one more of a specific legendary to ascend it? that is 100 x 1000 = 100,000 souls
Miss a mythic when they launched? It will run you 150 x 1000 = 150,000 souls a pop. I’d also suggest raising mythic disenchant to 250 from 150, so it would cost a quarter million each.
That way when I open 50 gem keys and get 0 useful troops, at least I can disenchant them and make progress towards the few I do need.