Omnistone is bad; here's how to make it less bad

Omnistone is the new RNGfest keystone. As anybody who looked at all the keystones may notice they focus on different things, whether the AS goodness of HoB and Lethal Tempo to the tankyness of Aftershock or the utility of Glacial. If you may also notice, most champions don't give a shit about some of those options.

Now, Omnistone does have 1 unique property; keystone effects are boosted based on Dark Harvest stacks. This includes things like Glacial's slow or Fleet's healing. This is an interesting, unique property but it's locked behind rolling 1 of 12 keystones (or 1 of 13 or 1 of 14, depending on if you have boots and a basic ability that CC's). And after rolling 9 (or 10 or 11) keystones it resets. You can go an entire game never seeing Dark Harvest, and even if you DO see it you need to quickly proc it on a below 50% health enemy to get any benefit.

In practice this means you might get 1 or 2 souls in a full length game. Obviously this isn't that special then; you aren't going to notice any change from 0 DH stacks Omnistone to 2 DH stacks Omnistone. My suggestions is to change Omnistone's scaling to work either based on Total Keystones Used or based on Total Unique Keystones Used. What this means is getting, say, Hail of Blades or Lethal Tempo on Urgot isn't a waste of a keystone now; using them up will boost your other keystones by a bit.

Granted, numbers will likely need tuning. I also don't expect this will make Omnistone anything other than niche; it can't be relied on and even at stronger numbers, getting Glacial Augment mid fight or Hail of Blades on a mage means you just don't have a Keystone for the fight. But it'd at least make it somewhat fun as a scaling meme keystone, because as is the only use for Omnistone is trolling.