Summon Allies bug ?

[Hood]

For unknown reasons, I cannot summon allies. Before the fight, I saw that such a possibility existed. Apparently there is a button? What does it look like and where is it located? There's nothing like that in my final fight...

[jennireneex]

The button for me is right above my weapons on the UI and has text below it saying "Call Forth Allies" . It is available after meeting everyone in High Hall and seems to work right up to the final phase ( entering the brain for direct battle ) of Act 3.

[Hood]

I was so pissed about this not visible for me that i nuked the brain with gale from orbit.