I got 26(!) useless Viral Keys from the last Sacrifice Event, but I need one more Infernal Key, because I was stopped at 299/300 counts to finish the achievements to get the Legendary Cosmic Soul.
It would be VERY usefull to change keys to the ones needed most.
Now I need to spend 250 (!!!) Frontier Coins to finish the achievement (I don't talk about all the other Frontier Coins needed to get the other new keys and toons).