Square Enix promised that there would be a summon in the Episode Duscae demo, but they also mentioned that it wouldn’t be Titan.
Indeed there is one, and indeed it isn’t Titan, as revealed by Famitsu in its preview.
Since it’s a pretty big spoiler, and I’m sure there are many that don’t want to know before actually playing Episode Duscae on the 17th, I will not write in this page who the summon is.
If you really want to know, I’ll make you work for it. Go to the search box on the top right of the screen on this page, and search for “annuncing” (yes, typo included, it slipped through the cracks back then, but now it’s coming in handy).
Once you see what article that links to, all will be clear. Before you do so, though, think about it. Are you really sure you want to know?