[K]

The "middle" gods are for when you need a god who can survive a late-game battle and/or ritual casting. Let me explain:

The middle gods tend to be for very specific builds, like a person that only wants 1-2 colors on a god and have them be very big for specific spell purposes (like casting Wish or Utterdark) or blesses.

So you use them like this:

In a late game battle, some fights really are decided by "destroying the battlefield". For example, someone might cast Foul Vapors or Astral Tempest, and generally in those situations everyone the field (both friend and foe) dies. The smart player does this to kill a few of his mages and troops, and a lot of his enemies. If your god gets killed in one of those, you feel pretty dumb.

Assassination or damaging ritual spells can also easily kill a weak god, so blowing some extra design points to prevent a god death (and a permanent loss to all colors of magic) from something like Fires From the Sky or Earth Attack is very cost effective.

Some of those gods also have weird extra powers. The Frost Father, for example, has a very large Chill effect, making him almost like a battlefield enchantment.