Final Fantasy 11
Round 1: December 11, 2013
Rounds 2 and 3 will be in some time in 2014.



Sage Hourou from DQ10 has shown up in Vana'diel. It's not clear exactly what the requirements are, but if you do certain things, you can become a slime in Monstrosity and also get some slime equipment.



Spriggans from FF14 have also mysteriously shown up in Vana'diel, and apparently you'll also be able to use one in Monstrosity and also get some spriggan equipment as well.
Dragon Quest 10
FF11 part will run from mid January 2014 to mid February 2014.
FF14 part will run from mid February 2014 to mid March 2014.


Shantotto has shown up in Azlan village and needs help finding materials for her black magic. If you help her out, you can get a chocobo cap.


Kupuru Kopo has also wandered into Astoltia from Eorzea looking for a particular flower. Helping this fellow out will apparently get you a cactaur hat.
Final Fantasy 14
Scheduled to run from mid January 2014 to mid February 2014.


Shantotto has also appeared in Eorzea, as a giant for some reason. She'll be a FATE boss, and the reward is a totally adorable Shantotto minion.


Golems from DQ10 have also appeared in Eorzea. This one looks like a pretty crazy FATE with a golem, a gold golem, and a stone golem. The reward is a golem minion!
Source: http://www.4gamer.net/games/005/G000546/20131120036/