From Blizzard Entertainment
Read the original announcement here.
How are the 16 participants selected?
The Blizzard Entertainment eSports team will consider several discretionary factors when selecting participants for the Invitational. This might include your overall performance on the SEA/ANZ Battle.net, your rank within your home country, and any tournaments you might have won. The invitees won’t necessarily reflect the top 16 ranked players. As the region is very diverse, our plan is to ensure that every country is properly represented by players at a highly competitive skill level.