I had that Bloodwar boxed set back in 2e days, and it was really nice. Unfortunately, I was never able to put it to much use.
On a homebrew world, the PCs were a big force. They were all around level 14. They'd just defeated the BBEG, who was the nemesis of their campaign, and were moving on to bigger and better things. I had this AWESOME Blood War thing ready, as in it was going to spill over and engulf the world if the group didn't find a way to stop it.
The chances for success were slim, but I was sure the PCs were up to the challenge.
Then, a lot of crappy issues with their "backstory" came up now that the guy they were battling was dead (he'd brought them together for a common cause, ect). They each wanted to do their own thing, and it came to a head that they freakin' went to war with each other. So, they all pretty much ignored all of the plots and quests and signs. Only the cleric paid enough attention. It ended up that as all their forces were battling with each other, massive portals from Baator and the Abyss cracked open and the fiends waded in and destroyed the world. The cleric wisely escaped to Sigil as this happened.
I got so mad, I scrapped the homebrew world.
I really wanted to run some Blood War stuff. Mortals can't influence the War on a grand, planar scale.. but maybe, just maybe.. they can save their own world from getting caught up in it.