Best covert spellcaster stories?

[Reprimand]

What the most effective sneakiest or clever use of spellcasting (particularly any in combination with niche items or feats) you've ever seen? Stuff like Charms, Divinations, Fears, Illusions or more obscure stuff like oneiromancy. Not your fireballs, black tentacles, and persisted buffs thread.

For me I had a player classed into Nightmare spinner and single handedly capture a major leader through clever use of an ingested poison the night before, gaseous form, mundane disguises, some skill checks, Inspire fear, Nightmare Phantasm, Spirit Chill, a single cast of major illusion and invisibility, still and silent spell feats, fell frighten fear and a well placed sap sneak attack.

[Venger]

Once, I played a chameleon. In disguise, he infiltrated a cult led by a powerful undead monster, replacing his lieutenant. The rest of the party attacked the lair and combat began. My character asked the monster to lower his sr to receive a buff (stone bones) before fighting the party. In actuality, he used false theurgy and cast spark of life on him. The party rogue then immediately killed him with a sneak attack. Good times.

[lylsyly]

Tibbit Totem Druid allowed by DM to take natural spell at level 1. Pretended to be a Sorcerer's Cat Familiar. DM was pretty awsome about not meta gaming. Bad guys never could figure out where the entangle spells were coming from. And when needed there was always turning into a bear. Strictly a trick for E6 or E8 games though.

[MaxiDuRaritry]

This was at about level 15. I was playing an evil blue goblin shaper psion/constructor that specialized in astral constructs and had a rather questionable past. The party got waylaid by a dracolich, which was in the thrall to one of my character's former employers who had found some extremely powerful artifacts and was now after me to settle a grudge.

The party cleric managed to land a spell on it and blinded it, but it managed to paralyze me even so. Since I was a psion and not a wizard (and thus needed no V/S/M components), I manifested astral construct to create a large enough construct to snatch my paralyzed self up like an oversized football and get to cover, but the dragon obviously knew where I'd gone, since it still had blindsight, but once I was out of line of effect, the construct stuffed me under some leaf litter (leaving my eyes uncovered, but not much else) while I ramped up the action economy and created a ton of me-shaped constructs, one of which the big construct snatched up and ran with (which the dracolich wasted a couple of rounds destroying, giving me more time to manifest more constructs, as well as a few other preparations, such as manifesting psionic grease on the ground beneath the dracolich), while the others were running around like headless chickens, trying to avoid the attacks of the pursuing dracolich, which didn't know which was me because blindsight couldn't distinguish color or fine detail. While that was happening, I manifested some really big constructs (which were immune to the dracolich's nastiest abilities) to grapple it and slow it down while the party caught up. Between my grappling constructs, the little distractions, the cleric's (greater) bestow curses to neuter it, and the party warblade's maneuver damage, we managed to take down a threat about 10 CRs above our ECL.

Of course, it wouldn't have worked without the blindness, but I'm still proud of how I managed to fend it off by myself for several rounds while completely paralyzed and ostensibly at its mercy.

[Telonius]

A team of five young-ish chromatic dragons were flying in formation, Blue Angels-style, heading to a particular section of the town. What was supposed to happen, was that the players rush off to fight them, with serious danger of collateral damage in a heavily populated area.

What happened instead was an Enlarged Incite Riot.

One round later, three of them had failed their saves (truly horrid rolling), and what was supposed to be a tough encounter literally crashed and burned. Even though the spell duration lasted just one round, the dragon siblings (who never completely trusted each other anyway) turned against each other, each one assuming that the others had planned treachery. The PCs waited to see which one won, and picked it off easily.

[denthor]

You kill what you think is a wizard turns out to be a Sorcerer. The "spell book" is 50 shades of the grey wizard. Filled with adult pictures.

[aglondier]

You kill what you think is a wizard turns out to be a Sorcerer. The "spell book" is 50 shades of the grey wizard. Filled with adult pictures.

Yoink...I am so using that...

Anyway...in a modern era game...used multi-sense illusion to cover up the feel and smell of pouring a can of petrol all over the enemy boss. He disregarded the visual image as an illusion intended to intimidate and gave us a five minute lecture on the effective use of illusion magics...to which our response was to throw a lit zippo into the puddle around him. We later used his advice to con our gm into giving us a bonus to our intimidation through illusions.

[AnimeTheCat]

The Enchanting Courtesan prestige class from Pathfinder is excellent for this. You roll bluff and slight of hand to mask your spellcasting against all people who can see you (they roll perception and sense motive). You can only use it with Divination and Enchantment spells, but it's fantastic to spin Charm Person, Hypnotism, Bungle, Discern Next of Kin, etc in to conversation.

No specific stories, but I'm really enjoying doing this in a game right now.

[weckar]

It's not exactly what you mean, but I once played a caster without anyone knowing about it. I never cast spells (where anyone including the party could see), and mostly just went at them with a mace in heavy armor. So, I was a covert spellcaster.