We learned late last year about an upcoming law in China, scheduled at the time to go into effect on May 1, 2017, that would compel the makers of games that use randomized "loot boxes" to publish the odds of various bits of stuff falling out of them. Last week, Riot got ahead of the big day (which is today) a bit by publishing the drop rates of its Hextech crafting and loot boxes on the Chinese LoL site. Loot boxes were first added to League of Legends in the 2016 season (opens in new tab).
Bear in mind that this information comes via Google Translate's OCR scanner on my phone, since the data was posted as an image rather than straight-up text, and so it's probably not going to be the most precise translation you've ever run into.
PCGamesN ran the image through a different translator and came up with somewhat different results, and there are also arguments underway about what it translates to on Reddit, although there does appear to be general agreement that Google Translate is not the best way to get from Chinese to English. Redditor NeoThermic took a crack at it, and their results jibe pretty well with ours, so for now we'll go with that:
Hexes Trophy Reward Probability
Dear Summoner, Purple Portal bonus content is as follows:
- Skin Debris (Skin Shards): 45.135%
- Permanent Skin: 29.255%
- Hero Debris (Champion Shards): 14.61%
- Permanent Hero: 7%
- Summoner Icon: 2%
- Guarding the Skin (Ward Skins): 2%
Here's an image of what a Hextech chest looks like on the North American LoL client.(opens in new tab)
PvP Live pointed out that permanent heroes and skins only drop in event loot boxes, so it's possible that these numbers are specific to special events, rather than general play. On the other hand, several Redditors also noted that the drop system in China is different than in NA and EU, so while there may be some similarities (you're probably going to see a lot of skin shards), you may not want to bet the farm based solely on this info.
I've emailed Riot for clarification of the numbers and where they apply, and will update if and when I receive a reply.