Funny...
I suppose I should justify, but I'm not sure why...
I'm converting part of Greyhawk Ruins right now. On the level that the Greyhawk Demigods were imprisoned, there is a Diamond Golem that defends the area, and a sizable portion of Zagyg's treasure.
It increases in power as light shines on it.
My group has finished the RttToEE adventure, and after a few other adventures, they are currently around 18th level.
The challenge is to create a creature that is nearly indestructable. The will of a mad demi-god.
I really don't want the PC's to win at all. I want them to run! I really like the Monsters of Faerun idea of True Strike and Dispell Magic. I'm going to increase the size of the golem by one category and add a few feats, like Quickened Spell-like ability for the True Strike.
I'm also going to try and incorperate the increased statistics for greater light sources... in the end I should have three versions of the golem, although my party is going to end up fighting the hardest one because a few of them still use light to see.
If I actually make a stat block(s), I'll post them here later.
Aluvial
Hey - I'm doing the same thing right now - converting WGR1 to pathfinder. You willing to share your notes?