We still have two of the original players, me and my best friend (who joined a few years after the campaign started).
So...Orcus is an ongoing major evil in this world. At one point, there was a massive war when he was brought to the Prime Material Plane and tried setting up shop on Taladas. The evil nation of Golgotha is run by a vampire lord, and it is one of the last strongholds of the Church of Orcus. They were instrumental in gating him into this plane.
During a continent-spanning war, a lot of crazy stuff and a lot of destruction happened. Eventually, with the aid of lots of followers (many now dead), some brave PC sacrifices, and the armies of no less than 3 nations, along with several artifacts and relics, Orcus was defeated. He was imprisoned in a special magical sword designed to hold his essence, like a phylactery. The sword was stolen by a demon who was trying to set Orcus free, hoping to end up in Orcus's good graces. The PCs followed him to the Abyss, defeated the opposition (barely!) and freed an imprisoned planetar. The planetar sent the PCs home, and vowed to keep the sword safe for protection so that Orcus would never escape.
Unfortunately, after the PCs left, a balor and his minions decided that the planetar was not leaving the Abyss with the Orcus sword. He wasn't leaving the Abyss, period!
So, unbeknownst to the PCs, the demons of the Abyss got the sword and have freed Orcus, who is vowing a most hideous, horrible revenge. His minions on Taladas are scouring the globe re-activating ancient unholy sites dedicated to Orcus going back centuries. When enough of these power spots are activated and blessed (cursed?), they will be able to summon Orcus back to the Prime Material Plane.
So the PCs, through a bit of luck, discovered that there were strange things happening on a distant island located beyond the Fog of Death in the Sea of Green (a Beatles homage - no, I didn't put Blue Meanies there!). They braved the undead and ruins atop the island, and eventually found the dungeons where the priests of Orcus are making human sacrifices. After a tough battle they almost lost, they had to retreat by sea with a handful of sailors they rescued from the dungeon, and get reinforcements. They're back now, but the priests of Orcus are ready for them!
Just got done with tonight's session, and boy are we in trouble! We have my character, who is a Kagonesti elf ranger/druid (I allow that for this game, long story), a Tamire elf wizard, a lizard man fighter and a human fighter/pirate. Levels range from 10th to 17th.
We made it down to the 5th level of the dungeon (lowest level). Got our asses beat up fighting 2 very sneaky vrocks. When we got past that and started to explore Level 5, someone messed with a pile of rubble that collapsed on a gate to the Abyss. Well, the abyssal ants are coming through now. In fact, 160 of them just started swarming outside the pile. Abyssal ants suck! They have 3 HD, 2 attacks, can spit acidic poison, and tend to swarm individual creatures. Did I mention that they're fucking fearless (Morale 19-20) or that anyone devoured by the ants is permanently and forever dead? Can't even be reincarnated or resurrected.
We have no wish spells at the moment, nor are we likely to find one. So they get 360 attacks per round.
Did I mention that the wizard walled them off with a wall of force, or that when we ended the session, the wall was about to dispel as its duration has run out? Did I mention that we're all stuck in a dead-end hallway with 6 tiny rooms (priests' quarters) lining each side? Nowhere to run to, nowhere to hide.
Next session should be interesting. No more "wall" spells left. No oil to burn them with. No Bigby's Massive Can of Raid spell.
Eh. At least they're not magic resistant.
But we have our work cut out. God, I hope the priests of Orcus don't appear and start commanding the ants and join in the battle. If so, we're doomed! 
