We're pinned in a rather plain belltower, the streets are pretty much flooded with zombies. There's random houses that are boarded up, and the church is heavily barricaded, but we have no guarantee that anyone is actually in these places.
We're at the top of the belltower, the wind is picking up and it's obviously about to storm hard. The zombies are circling us. They're not completely thick around the belltower yet, but they're COMING, and it's just a wall of corpses past the few gaps anyway.
The relatively weak barricades we threw up start to give, and then finally let go with a whimper. The zombies come shambling in, moaning hungrily. Lots and lots of them. Even if they're all mook-strength, we're going to have a hard time with the numbers alone.
The duskblade, no hesitation, jumps up, grabs a wooden beam, and gives the rope holding up the big heavy metal bell a quick swip. It falls, tears up the internal structure just a teensy bit, and pancakes a bunch of corpses. It also acts as a choke-point in the bottom of the tower itself, so we basically are seeing LINES of zombies coming up, instead of mobs. So that's a little good, but we're still in bad shape.
The archivist comes up with an idea, and gets the DM to agree to it 'behind the scenes' (read: in notes).
Now, in our group? Prepared casters tend not to prepare all their spell slots unless they know something's coming up. If we're about to trek through the woods, they'll fill their slots with buffs and useful stuff of course. If they know they won't get a chance to prepare spells later, they'll fill it up with what they think will come in handy. Otherwise? They leave their spell slots open. It still takes time to sit down and ready them all to be cast, but personally, I kind of like that. It makes magic something a little more cinematic and a little less "machine gun"ish. Spells take time to prepare, so if you have the time, you can prepare what you need. Otherwise, be ready with your best guesses.
Our archivist has his spell slots unprepared. So what does he do? He touches the paladins shoulder (in and out of character) and says "Buy me some time. I need to pray."
The dragon shaman, leaning over the railing and looking down at the corpses groaning upwards at us, says "Yeah, we ALL need to f***ing pray".
So the archivist kneels in the corner, prayerbook open, wind whipping throughout the wall-less area we're in, while the rest of us try to find ways to make ourselves useful.
The paladin rushes down the stairs (actually cackling 'heroically', would be the best way to put it) spinning his sword above his head. Takes up a natural chokepoint on the stairs and starts trading blows with corpses. The Duskblade/Swashbuckler readies herself behind the paladin and curses about not having a reach weapon. The dragon shaman keeps a little distance, but gets in aura-range of the paladin and puts up some damage reduction for him. The warforged bard sits calmly at the top of the stairs and begins a creepy flute song (...), and I perch on the stairway higher up and start plunking stuff with my crossbow.
This goes on for a while, the paladin is taking some injuries, but is still fighting like a pro. The bodies are piling up in front of him and slowing the zombies down, but also confusing matters some (they all look dead anyway, I can't tell what I'm chopping at! It's just a wave of teeth and rotten faces)
Finally, the archivist shouts down "I'm ready, I still need more time!"
And starts climbing outside to get to the pointed roof of the freaking belltower. In what's about to become a torrential downpour. Lunatic.
I ask what in the nine hells he thinks he's doing, and he says "Hemorrhaging divine magic, just get me time!"
The thing is, he wasn't just casting spells. He was giving spell slots, but he was also asking for a miracle in a way. He's perched up there, clinging to a lightning rod (!!!) and reaching up towards the sky. Fog and vapour are drifting past, and he's running his fingers through it, mumbling chants and giving up his spell slots. All of them. For?
The storm breaks. The DM makes him roll a reflex save (failed) and takes heavy electrical damage, and is temporarily deafened, but survives it. Slides down the rooftop weakly, the bard grabs him and pulls him in, and the downpour begins.
The downpour with faint but present traces of holy water throughout the entire cloud system. Oh yeah.
Apparently, the archivist got his miracle. He gave up his spell slots for the day... ALL of them, to pour as much divine and personal energy into the air as possible. He cast Bless Water a few dozen times in every spell slot he had available (except 0 level) and prayed that it would distribute throughout the clouds. And it did.
It wasn't KILLING anything, it was too diluted. But the zombies were flailing and collapsing in divine agony. The more vaguely-not-stupid ones shambled for cover, but most of them just collapsed groaning in fury.
And it got us what we needed. With the warforged bard carrying the injured archivist (yeah, not anything in D&D rules, but the DM and us all agreed that he wasn't going to be sprinting after getting hit by lightning, high level or no), we broke for it. We fought viciously through the zombies still in the belltower and broke out into the rain.