Udyr with more info:
"Get ready for three days of League action because we're cranking up the IP gains during the last weekend of April!
From 12am on Friday April 25th until 11:59pm on Sunday April 27th, you'll earn double IP from every match. This should up your mileage from the 30% off Rune sale that's running through the last day of April.
In addition, we wanted to give you advance notice that we'll be having a two-week long 2 for 1 Rune Page sale during May. The exact time frame will be announced at a later date, but if you want to take advantage of the promotion, start saving so you can snag the rune pages you need."
On Twitter, Udyr confirmed the participating regions as NA, EUW, EUNE, TR, RU, and OCE .
As for LAS/LAN and BR, he explained:
[ Tweet 1: For some extra context, Latam won't be in this round because they already had a double IP weekend earlier this year. ]
[Tweet 2: Actually, clarification on the BR IP weekend, its actually because of major esports event. They will have the IP weekend a different date.]
As for seeing these sort of events more frequently, Udyr commented:
"We've been slowly catching up on a server capacity/networking perspective, and there was an good open weekend to do one.
We'd like to do more Double IP weekends in the future, but there are a lot of factors at play, so I can't commit to a specific cadence."