The Japanese manga magazine Weekly Shonen Jump posted the first picture of the summon players will be able to use in Final Fantasy XV‘s demo Episode Duscae.
Since it’s a rather relevant spoiler you can click on the link below to see the picture. The file name will give you the name of the summon if you’re not familiar with the series (so if you don’t want it spoiled, don’t even hover your mouse on the link).
The text explains that the summon will be available under specific conditions, and that summoning won’t be the same as in the previous chapters of the series, possibly indicating that we won’t be able to summon our mighty allies at will.
[Thanks for the tip: Choro]