Have a ton of IP laying around? Not sure you'll have enough for Urfwick when preseason hits? Gamble.

Riot revealed that with the IP changes coming up this preseason (complete removal of IP and full switch to Blue Essence as the new currency), they will be multiplying all Blue Essence that you own at the time of the switch by 6.5, in order to give it a decent value.

What does this mean? Well, 1 Blue Essence (BE) will become 6.5 BE (Or 6. Or 7. Not really sure how they'll round...). 10 BE will become 65 BE. 100 will become 650. And 262 BE will become 1703 BE.

Wait... That last number seems a bit random, right? Well, if you all recall, Mystery Champion Shards cost 1700 IP. When you unlock the shard, you get a random champion shard that is worth a certain amount of Blue Essence - apparently ranging from around 100 to 400. Since 262 Blue Essence will be multiplied by 6.5 to equal 1703 when the update hits, any champion shard worth that much or more will actually give you more currency than what you paid for it!

Go out there, buy some Mystery Champion Shards, and gamble it up!

Edit: It turns out, it isn't even that much of a gamble - any 3250 IP champion or higher will give you more than 1700 BE after the update, meaning you have a 75% of earning more than you spend!

Also, someone on Reddit apparently beat me to it - there is some additional information and maths and stuff here.