During my time with the new hextech crafting on the PBE
As i was just testing the hextech systems i begin to understand how the crafting and earning of loot though unboxing.
Opening the box can give you: 1 skin shard 1 champion shard 1 Ward shard so far i have got 150 essences of each type twice, But they also come with a free icon you get for free 1 rare shard, which can be turned into a box and key.
After opening 11 boxing i got a legendary skin so the rate of them dropping seems to be higher then most would think. I have come to see the shards are tokens and by that i mean that if there is a token you want you can use your unwanted tokens to get the essences you need to cash out, When you break down shards you get the type of essence of that shard so champion shard/ champion essence. The amount required is fair with higher skins being up in essence cost to make the essences you get from higher priced skins seem to always be enough to get any tier below, so breaking down forecaster janna cause you don't play support so you can get arcade sona you will have enough for the process and enough left over for maybe a 520 skin.
Lastly, As i have all the champions on the pbe if you try to make a random champion with all the champions unlock it will just error screen you so theres that, so when you get to that point keep three and break down the rest, when i new champion comes out use the three for a re-roll and get the new champion cause its the only one left in the pool to get.