So, the players in my game have progressed enough, and ruined enough plans to finally get themselves on the radar of some fairly powerful, and intellegent foes.
Naturally the first course of action of any rational thinking entity is to find out exactly what it is dealing with.
After some digging around, the PC's base has been discovered by the Bad guys, and, determined to find out about the capabilities of these "adventurers" they do what bad guys do best.
Call in some favours, and sacrifice an army of minions in order to draw the PCs out.
Spoiler
The two half fiends watched impassively from their perch as the various minions they had brought with them tore through the ranks of the Kobolds below.
"It's not much in the way of a base is it, Na' Tas?" asked the first, in a somewhat derisive tone.
"Were we much different when we started out, Raziel?" replied the second.
Raziel raised his voice slightly so as to be heard over the screams of one unfortunate reptilian being quartered alive by a pack of succubi.
"I suppose not" he began "But even in the early days, we knew what style was, Na' Tas. I mean... just look at the place!"
Na' Tas Shrugged as he cast his darkly glowing eyes over the scene below them. Raziel had a point, it was little more than a ruined elven city populated by the ragged remains of a Kobold tribe. Not exactly the bastion of defence they had expected when they followed the leads here. Below them their demonic horde was blissfully slaughtering the pathetic little creatures in ways even he wouldn't have thought possible.
"It does lack a certain degree of... elegance, I suppose" he conceded. "But then... I don't think they spend much time here, Raziel. It looks like they leave those two in charge"
Na' Tas's clawed finger pointed over the way towards two individuals. Around them, the battle fared somewhat differently. Surrounded in a not insignificant aura of power, they lay about themselves with various magics. The Fiendish bard quickly wracked his brains and recognised many of the spells they were using.
"That was an orb of force the half dragon just flung, Raziel"
"Indeed Na' tas, and the Kobold shaman is using them as well. But her's are empowered."
"There goes a wall of force, Raziel"
"Noted, and that was a twin, empowered, magic missile, Na' tas. All in all I am not impressed, we two alone could deal with these hedge wizards"
The pair watched as a Succubus dropped from the sky. The grey tinge of stone quickly spreading across it's body. It shattered into fragments as it hit the ground.
"Flesh to stone" The duo said at the same time.
"Ahh" exclaimed Raziel "And there is a sending, Na' Tas... not long now"
Not six seconds later, there was a whip crack of supersonically displaced air as the objectives of this little excursion teleported directly into the carnage
"And here comes the cavalry, Raziel" whispered Na' Tas, with a grim smile that revealed his fangs.
Things down below changed dramatically, Within moments, the scruffy looking robed human transformed into a huge bear and begun tearing demons to pieces. The high elf spellcaster was obliterating whole swathes of fiends one spell at a time, the northern elf with twin swords was a whirling engine of death incarnate, and the armoured dragon-born and elf female were brandishing symbols and banishing outsiders ten each at a time.
"Now THESE folks are interesting, Na' Tas"
"Oh yes, Raziel. I would wager these are the ones we need to deal with carefully"
"Indeed. I have seen enough, Na' Tas. Let us go and prepare"
"Agreed, Raziel. I have much preparation to undertake and have also seen as much as I need to"
"Can you do it, Na' Tas? are you sure you can deal with these adventurers?"
The half fiend smiled grimly as he flexed his pinions.
"Oh Yes Raziel, they wont even know they are under attack."