I wanted to run a fight where position would be the most important element of the battle. Here's how I approached that goal.
The fight was against the high priestess of Hyacintho, who had issued a direct challenge to Kord in order to prove that her god was more powerful. By SHEER COINCIDENCE, the party (and specifically Kalgar, paladin of Kord) happened to be around. Check out Dallas' post if you want to read about how the fight went down.
You can find the stat blocks I used on the right side of the page.
You may have noticed from the names that both stat blocks represent the same creature - the high priestess. That trait - Empowered by Lightning - is the key to making this fight interesting. The high priestess wears a harness with wires running to the brass plates on her feet and the brass spikes on her palms. As long as the contact on her foot touches one of the brass rails inlaid into the floor of the temple, she's powered up by the lightning running through the rails. Or, mechanically speaking, she uses the Empowered stat block whenever she's in the same square as one of the rails.
Important to note with that trait is that it activates only at the end of an action that moves her on or off the rail. This is to avoid any confusion as to which defences or reactions she uses against, say, a Tide of Iron that would push her off the rail. If she's on the rail using the Empowered stats and a fighter attacks with Tide of Iron, she uses the defences on the Empowered block, and has the option to use Lightning Reflexes to avoid the attack entirely.
Speaking of which, if Lightning Reflexes moves her off the rail, she drops to the default block at the end of that immediate action. If the Empowered priestess his hit by an area attack, and uses Lightning Reflexes to move off the rail but still within the area, she drops to the default stat at the end of the Lightning Reflexes move - which means that the area attack is still ongoing, and she'll use the lower defences of the default block.
But what's all this about rails? I used a custom map for this battle. In the centre of the map is an altar, and radiating out from the altar in all directions are brass rails that conduct electricity. These rails are close together around the altar and farther apart around the map borders.
So basically, the high priestess wants to be on the rails (ideally in the centre of the map where she has more freedom of movement), and the party doesn't want her on the rails. To use her lightning powers she needs to be in the right place on the battlefield, and pushing her around will force her to use her weaker, unempowered stats. One of the most important elements is her aura, Spark of Raiden, which will automatically deal lightning damage to nearby enemies. But since it triggers at the start of her turn, if she begins her turn on the weaker stat block, the aura doesn't trigger and there's no lightning damage. It's hard to prevent her from using her lightning powers entirely, since it's tough to completely lock down an enemy, but with the relatively wide availability of pushes, pulls, and slides, it shouldn't be too tough to keep that aura away.
(I seem to have misplaced the stat blocks for the Ball Lightning mentioned in some of those powers, but they're just minions that deal automatic lightning damage to adjacent creatures, and can't take actions on their own).
When I ran the fight I was a little disappointed at how easily the party was able to push her off the rails and prevent that aura from activating. On the other hand, it made them feel pretty badass to handily defeat the religious leader of an entire country that follows a false god. So that's good!
(and yes, I know that despite the title, technically this is an elite monster and not a solo. But I ran her on her own, so she's sort of a solo, right?)