Board Thread:Question and Answer/@comment-114.79.58.211-20150619155921/@comment-25151790-20150619204806

You might be fighting your comrades' Archwitches. In that case, you won't find a "Reinforcements" button, as you can only call for reinforcements for your own Archwitches.

If you are fighting your own Archwitches, then this is probably a bug and you should report it.