Some scholars have speculated that the the extent of warfare over previous generations has built up a "negative" energy surplus, which is what is responsible for not only the commonness of undead in certain parts of the world, but also for the ubiquity and aggressiveness of other kinds of monsters in formerly inhabited areas. Others have argued that these changes are simply a result of the waning influence of humans in many remote areas, who in the past were an effective enough deterrent to these monsters from wandering too far afield from their own dominions, but now are too weak to have the same sort of effect paired with the unchecked activities of necromancers and other evil magic-users. Regardless, it is true that kobolds, goblins, orcs, and other humanoid threats, which were once nearly exclusively subterranean in their habits, have begun spending a considerable amount of time above ground, harrying caravans and impeding the rebuilding effort of many abandoned cities, trading their weakness and sensitivity to light for sheer numbers in their raids.
Encounters with insects, rats, and other scavengers, grown to enormous size, are increasingly more frequent, leading many to believe that they, too, are the result of crazed experiments by wizards. They have infested many otherwise habitable buildings, so as people move back in to the abandoned cities there is often a dangerous and time-consuming fight with the beasts in order to render the places fit for human occupation once again. Many prospective homesteaders will pool together their money to hire a group of adventurers (or mercenaries) to root them out.
Some necromancers and wizards have rendered regions all but uninhabitable, but the total number in either nation that can cause significant, potentially world-altering difficulties probably number under ten. The worst problem are the less powerful, but ambitious wizards who might be a little more overzealous and audacious in their pursuits for power. These corrupt wizards carry out strange magical experiments on usually unwilling individuals, creating monstrous abominations out of formerly human subjects, either living or dead, and occasionally both. There have been unsubstantiated reports from some remote areas of terrible beast-men having been seen hobbling around, obviously undertaking some ineffable errand for their wizard-masters. Despite the fact that many of the world's problems are probably directly attributable to wizardry, evil wizards themselves are practically never encountered. They choose to hide behind their works, holed up within their towers and freeholds, protected by their own magical wards as well as, frequently, the bureaucracy and good graces of the empires, which themselves turn a blind eye to all but the most gratuitous violations of human decency.
One of the stereotypes of evil wizards is that they traffic with beings
far beyond the ken of ordinary mortals, and draw even more power from
these dark dealings. Sometimes, this is even slightly true. Many wizards
will have devils or demons bound to them as advisers, protectors, or
even servants; their estates may even be protected by hell hounds,
worgs, or blink dogs. It is beyond the capability of even the most
powerful wizard to control a baalrochs, but some nevertheless fool
themselves into thinking they can maintain a "mutually beneficial
association." Even the lowliest of devils will not willingly serve a
human master, and will readily turn on them when presented with free
will, a change in conditions that is no longer beneficial to their
interests, or simply a better offer from another interested party.
Indeed, many devils, once summoned into the world, will simply bide
their time until they can overwhelm their "master," and then kill them,
escape, and live freely in the world. Some even are able to maintain a
disguise or glamour and put themselves into positions of power and
Surprisingly, dragons, even great dragons, are a far rarer sight than ever before. While in the distant past there are countless stories of the devastation dragons could wreak upon towns and cities, nobody can now remember an instance in recent history where a dragon was even seen, let alone attacked any place. Some speculate that the dragons have entered into pacts with the leaders of the empires, and are being plied with victims and treasure in exchange for stability and protection, while others even go so far as to believe that the emperors have subjected even the dragons to their rule. It is up to the game master to describe what has actually become of the dragons; perhaps they are as more common as ever but dragon attacks are carefully concealed by government propaganda, or maybe they have entered into tenuous agreements with the corrupt and bloated governments and, for the time being at least, are sated by the frequent offerings of prisoners and gold. Regardless, dragon encounters should be exceedingly rare, and perhaps scaled up in difficulty even from where they are already to reinforce that they are incredibly powerful creatures, even in youth.
Finally, all manner of foul things, from slimes to jellies to toxic mold await adventurers in long-forgotten ruins or within underground caverns. These things very rarely are seen above ground, since the sun causes them to burn and evaporate very quickly, but as long as they are not exposed to that, they can be surprisingly hardy. They are seldom seen in association with other monsters, such as orcs or goblins, as they tend to want to clear the slimes out for their own safety when they take up residence in a new place. However, due to the special nature of undead (especially skeletons), slimes are much more commonly found in proximity to them, since they do not view each other as either a threat or as food.