Quote Originally Posted by Dhavaer View Post
Gate doesn't summon, though, it calls. Called creatures can summon or call other creatures.
Which creatures have Gate or Planar Ally as a spell-like ability? If they had that, then the infinite-summons problem becomes real. The first demon or devil gets called, but after that they can't call more, they have to summon. None of them that I'm aware of actually have the ability to call.

Basically, demons and devils have a percentage chance (except the most powerful, for whom it always works) to summon more demons, once per day for one hour. They can't summon more than that. Slaadi can't either, to my knowledge; one summons per day, total, is it--and the summoned allies disappear after an hour.