Note, this is your giveaway (2013):

https://steamdb.info/sub/28606/apps/

Which is different from this (2014):

http://store.steampowered.com/sub/49306/

The older collection is missing the Destroyer of Worlds DLC.

You should probably mention how you feel about people who own part of this package (base game, or some DLCs too) joining.
I only lack the very newest, which isn't included here.