I hope this has not been covered before. I've been reading this thread casually for a while, but not every page. I just got my copy of the WLD from Amazon today and i've been diving through it. Something that caught my eye immedietely was the bit about Monster Summoning. I can understand why MS has been nerfed, but, I think I have a reasonable way of adding it back in.
The Dungeon, of course, does not allow extra planar beings to leave. That's the whole point. So, it can be assumed that, over the aeons, extra planar beings of all types have been brought in and many have died. Normally, when an extra planar being dies, it simply returns to its home plane. However, that isn't true here. They cannot leave. So, what happens?
Here's my idea.
The extra planar beings are trapped in a bodiless state after they are killed. They cannot affect their surroundings in any way, and they cannot escape. When a caster casts Summon Monster, one or more of these bodiless spirits are made corporeal for a short period of time (the duration of the spell or until they are killed again, whichever comes first). Since extra planar creatures of all types have been trapped in the Dungeon, it can be assumed that any summoning spell is simply calling upon existing spirits. That way, we can still use summoning spells, without worrying about the party creating hordes.
What do other people think?