I want an invading army from beyond this dimension. Tell me about it.

[C.W.Richeson]

So, I want a short game where the focus is on an invading army from another dimension. I'm probably channeling a little bit of Feist's Riftwar Saga here, and I imagine the army coming in through great portals rent in the world.

The thing is that I'm just not sure what would make for a cool invading army. Githyanki? Dragons and Dragon-Hybrids? I'd definitely like to have some D&D flair to it, so to speak, so classic monsters and such would be especially awesome.

Sell me on your cool idea!

 

[Angel Tarragon]

Kromaggs for teh win.

 

[Freak of Nurture]

In descending order of silliness:

Modrons declare war on irregular shapes. 1st Ed. Monster Manual 2 and Planescape I think.

Roofdrak the Prime Canine and his horde of wolf-beings getting payback for the enslavement of dogs. Think he's from the 1st Ed. Deities and Demigods.

The Sultan of the Efreet or one of his generals decides to set the world on fire. Al-Qadim.

 

[Jack Daniel]

In my current campaign, now running on for some 15 months (with the player characters at about that level), the world is being invaded by unseelie fey, portaling into the world at random, Mortal Kombat style.

It all began when the bright-eyed and bushy-tailed 1st level PCs made an enemy of Randall Jakobin, an evil sorcerer who also happens to be the guildmaster of the assassins' guild in Pensula City. Randall had a plot to summon up some devils to be his allies; but the PCs showed up with a phlogiston bomb (read, the steampunk equivalent of a tac-nuke) that they had obtained from Jack Orestes, the guildmaster of a true neutral aligned thieves' guild which is an enemy to Randall's guild. Long story short, they saw Randall cast a spell to try and gate in some fiends, but before he could finish, they kicked him through the portal (effectively sending him to hell), and then they threw the bomb in (effectively nuking Randall, along with a significant portion of hell... not that that was the last they'd see of this villain, of course).

Problem is, they went and used high technology to counter high magic. There was a freaky-deaky reaction and the gate shifted from Baator to the plate of nightmares, and out stepped a tall fey woman who dropped the Gozer line ("Are you gods?") and then vanished. (The PCs didn't know it, but the woman was Morgan le Fey, queen of evil fey.) Thereafter, they went into the city and discovered that lanky hobgoblins with dragonfly wings were appearing out of portals everywhere and tearing up the city, and gremlins had overrun the airship field, causing all sorts of mayhem with every kind of technology. Ever since then, the whole continent has been going to hell in a handbasket, with evil fey popping up everywhere: pookas disguised as little children running through the streets and cursing people; redcaps on the highways going serial killer on all the random passers-by; nockers haunting mines and dungeons, and driving the kobolds and goblins up onto the surface in desperation (where they, in turn, have to rob and pillage to survive); and a fey troll under every bridge!

That's my campagin. I'm guessing the PCs are going to be 25th level or so before they can take on Morgan herself and end the invasion, as well as the pure *chaos* that the world has become.

 

[Trouvere]

Neogi! Tirbanas! What can I say, I like the bugs.

 

[Arkham]

Mind flayers. They've established beach heads in many deep, out-of-the-way places already. All in preparation for the arrival of their invasionary forces.

 

[Ry]

Really D&D heavy:

Githyanki have discovered that the players' homeworld is going to soon be ruled by illithids who will spread out like crazy. They have made an uneasy alliance with githzerai to destroy these illithids.

Githyanki AND Githzerai invading to turn the surface world into an outpost for their great war against the Illithid who live mostly underground. The illithid have infiltrated many surface societies, however, and so while both 'yanki and zerth want to maintain the lives of many surface dwellers (to serve as soldiers and workers) they are basically fighting a war of subjugation.

Githyanki play the Red Dragon card, Zerth make an alliance with some slumbering titans beneath the planet's moon... it could be freaking wild. Wow, now I want to play it.

 

[Jin_Kataki]

Jack that is possibly the coolest thing I have ever heard.

 

[NexH]

Somehow, ethergaunts (from Fiend Folio) really seem to fit the title of the thread: they are humanoid aberrations with great skills at wizardry and technology that come to the world (actually, return) from the ethereal plane, to eradicate all life.
However, they aren't "classic monsters" at all, and even the lowest of ethergaunts is a very powerful mage, so they won't make a "typical" army either.

 

[Twowolves]

Make 'em bugs. Give Thri-Kreen wings, use Dromites and Formians, and make them all psionic (preferably with the "Psionics are Different" option).

That's what I'm going to do.