If you didn't get a ban in LoL during 2014, you could be rewarded.
Do you play League of Legends? Were you a good boy/girl in 2014 when playing the game? If the answer to both of those questions is 'yes', then you could be entitled to receive a reward.
There are some certain requirements you need to meet before you could be given the 'Mystery Gift' spoken of in the announcement from Riot Games. First you need to be Level 5 or above, and there must be at least 10 skins you do not own. Plus you mustn't have received a chat restriction, ranked restriction, 14-day ban, or permanent ban in 2014. If you meet those requirements then you could get your reward in the next few days.
On a personal note, I think this is a great idea. Dota 2 is my MOBA of choice, I play it a lot, and with extended periods of playing the game comes the often laborious task of dealing with the less desirable members of the game's community. However, rewarding good behaviour with a "Mystery Gift" is a nice incentive, if you're a person that needs an incentive to just not be "that guy".