As you grow stronger/higher level you will be able to get more. Example: I have 14 I can summon atm. Can get them all but need sooooooo many of those Soul Shards to get the rest and or more Gold than I can afford right now. Patience young grasshopper, they will come.

I'm assuming you mean the individual Aesir. Your thread title is a little vague/misleading. Good luck with the game and have fun :D

Then it should show the max number of Aesir you can have at any level on the Valley. This way you don't just pick the easy ones thinking there isn't a limit to what you can have. Also i upgraded Valley from 18-26 with no change to the number i can have, so having to get palace to level 32+ or so shouldn't be the fix for this lack of information.