Bought 7 Event keys.
Clicked the button to open the chests.
Game crashed to desktop.
Logging back in, the keys were gone 
Sending a support ticket now
The contents of event keys, as far as I can tell, are fairly ordinary. If they opened properly and went to your existing troops, you would NOT notice. I opened 10 and didn’t even get a single one of the featured troop (Anointed One) - y’know, “You can win this!”…
I found gem and event key payouts to be lower than glory keys for the most part, lol. It felt like all they gave were ultra rare troops.