Sadly, will never happen. Shards are likely their biggest revenue source, and giving people a free way of getting them which doesn't involve chance or time constraints is out of the question.

I'm assuming it would work if say for example the x was calculated at the right percentage 

No. Kram is correct, never going to happen. 

But essentially they can be used as equivalents in chase and summon events for the requisite points. That is the best use of saving greenies.

I want a way to open a mystery shard and then have the champs immediately gone. I don't even care if I got zero value besides the event points. I HATE clearing out 1000 or 2000 shards worth of champs.

They give a lot of Exp in the tavern.

I wouldn't say alot :) but yes I feed all 1s and 2s to 3s. Open 80 at a time. It doesn't take too long to get thru 2000. I managed the last chase event with 3 sacreds and about 1700 green. And that got me the 1st lego book too.

I do wish there was a way I could just turn, like, 10 mystery shards into three 2* chickens :/