Is there a monster that could destroy a city or if not just cause great destruction.

a dragon will do mass damage

The only devastated city I'm aware of offhand is Mordheim. And that got nuked by a giant meteor of warpstone that came crashing out of the heavens.

That being said most cities are regularly destroyed by ... armies.

Undead, Orcs, Chaos, Dark Elves, Skaven, enemy lords - you name it, it'll smash it.

or again... if some cult managed to summon a greater daemon inside the city.

Someone could accidentally or on purpose open a gate to a realm of Chaos. That would pretty much allow you to do anything with that city.

I suppose it depends on what you mean by destroy a city

- leave a giant crater and nothing else -> probably a comet, or a Skaven atom-bomb equivalent thing. Wandering deranged High Sorcery master that loses his mind.

- leave smouldering ruins -> skaven devices, nutso bright wizards, greater deamons, warp fissures

- destroy with a biological agent > anything Nurgle related, anything liche-related

- destroy as in ransack -> Khorne related armies

- destroy as in flood > see Gathering Storm: floods & storms. Possibly tied in with Nurgle/Skaven viral agents

- destroy as in make into a magical pixie fairie land with pumpernickel roads like a Moebius Strip, houses made of incredibly strong wool where you enter through the roof with a shovel... -> Probably a greater daemon of Tzeentch

take your pick

I would still prefer a medium-sized Waaaaagh :-)

A nexus un-protected by a waystone (e.g., a waystone removed/unseated) would have gradually devastating effects (mutation) according to the Blackhearts novel series.

Rob

If you wanted something insidious as hell, you could always have a deranged (or extremely focused depending on your POV) Witch Hunter start a full-blown inquisition and witch hunt.

Start off small finding "Thrice-damned chaos worshippers" in some of the hinterland villages, and as he grows more deranged (and charismatic) he gains followers and devotees. Zealots, Flagellents, Thugs, etc. Until you have an entire army of religious nutjobs willing to slash and burn.

Oh sorry about that, was just reliving my halcyon days growing up in the South...

Some slann or another.

"Venerable Lord Kroak: The first Slann spawned in the world and the most powerful wizard in the game. His corpse is carried into battle, but his soul does the fighting, and is helped by his loyal mummified skink attendant that helps him fight in close combat. He was the ruler of Itza, the first city, during the Great Cataclysm and defended it for nearly a year before being destroyed by a host of greater daemons of Khorne, and yet his spirit lived on and continues to fight the forces of Chaos to the present day.

Lord Mazdamundi: Literally "light of the world" (from Mazda and Latin "mundi") The oldest living Slann and the most powerful living practitioner of magic in the Warhammer World, Mazdamundi is solely responsible for the downfall of the Dwarven empire by causing a massive continental shift that caused many of the holds of the Dwarves to be flooded by lava, and many of the others were overwhelmed by the greenskins that invaded in the aftermath of the disaster. Through sheer domination of will power he rides a mighty Stegadon into battle and his gaze humbles all but the mightiest of warriors."
- Wikipedia: en.wikipedia.org/wiki/Lizardmen_(Warhammer)#Notable_Slann

They could.

Thanks guys for all the suggestions

In my story there is a dark wizard and he is the main bad guy of this campaign. I want him to be very powerful and have a lot of powerful followers. I am not strictly following the lore on this one because this is a little outside the box of the war hammer world. But at the start of the camp a city is nearly destroyed but im not sure if i want it to be a army or by some creature. What do u guys thing is a cool idea?

This is very cliche and not strictly speaking lore but ....

A Warpstone "experiment" (the nature of which does not need to be revealed) that went horrbily wrong. The resulting effects are the levelling of a city block, or district, with an upsurge in mutation in all adjacent blocks, or districts. Given his proximity to the warpstone when it ignites, the rogue magician suffers terrible burns to his face and hands - only surviving by his shear willpower and grasp of the winds of magic - disfiguring him (extra challenge dice on social actions?).

This will render the city / town partially ruined, inhabited by mutants, survivors finding shelter in niches that they battle to control, a possible Skaven interest due to the warpstone involvement, a very nasty and memorable rogue magician (possibly with cultist links - Khorne or Tzentch), witch-hunter interest .... a whole heap of plots and sub-plots for PC's to enjoy.

Just some idle ideas to work with, and good luck with your campaign. Let us know how it goes.

Alp

i love that idea alp, so far the camp is called the Sage of the Seven Elementals and heres some of he backstory i wrote let me know what u thing.

The Saga of the Seven Elements

Long ago when the world was young, a group of mighty warriors walked the earth protecting the innocent and facing chaos and its minions. They were imbued with the elements of earth, fire, water, wind, lightening, light, and shadow. These warriors became know as the Elementals. With each new generation the power of the Elementals was passed on to the next person worthy of its power. Because of these chosen people the lands new a time of peace like none other. Until the rise of the dark lord Ameret. Ameret was a powerful chaos wizard, with many followers. After many years of battle Ameret and the Elementals finally came together in combat for the last time. The battle was one of legend and at the end the Elementals triumphed over Ameret. As the Elementals prepared to deliver the final blow Ameret swore that one-day he would return to have his revenge. Then out of nothing he created a gate to a chaos realm. The swirling gate of black nothingness seamed to be endless as it hissed beaconing everything around it to enter the black. The gate began to suck everything around it in and Ameret and the Elementals were consumed by the darkness. To this day no one had seen or heard from these ancient warrior or the dark wizard, will they rise again only time will tell.