Marshwalkers
A marshwalker is a large semi-humanoid creature that appears to be made entirely of plant material. Within the Empire they are primarily found in Bregasland, Kallavesa and Therunin, but they may appear almost anywhere that the marshy conditions they favour can be found. They are also found in the lands of the Druj, and the barbarians sometimes bring them along on battles. They are perhaps most dangerous when exposed to the essence of a vallorn-corrupted environment.
The creatures themselves are not common, and generally not a threat to humans who give them a wide berth. Unfortunately, their migrations often take them near human settlements - and the beasts show little inclination to detour around them. Attempts to divert a marshwalker exodus are complicated by their resilience, their resistance to fire (they are simply too damp to burn), and their ability to smash through most obstacles placed in front of them.
One problem with marshwalkers is that, in their natural state, they are simply a colony of little slimy blobs that are virtually indistinguishable from the mud in which they live. In this state they are no threat to anyone, being primarily concerned with eating small insects, fish and plants and splitting into more tiny, non-threatening blobs. It is only when they feel threatened, when some biological urge inside them decides it is time to move, or when someone starts building a structure near or threatening their habitat that the colony comes together to assume the much more dangerous form of a wood-armoured humanoid.
Appearance
Marshwalkers appear to be masses of vegetation coated and held together with thick slime. They are often encased in wood and stone fragments that appear from a distance to be nothing less than armour. The beasts seem to intentionally seek out this coverage in the same way that certain crabs seek the shelter of empty shells. Sometimes human-made elements may creep into this outer covering - pieces of plate, twisted swords and the shattered remains of shields have all been spotted woven into the outer shell of a marshwalker. Likewise, pieces of bone and wooden hafts are sometimes bound up inside the beasts in addition to branches and reeds, giving marshwalkers that have risen from near battlefields or passed through recent war zones a distinctly eerie appearance.
Studies by Marcher and Navarr naturalists have discovered that the marshwalker itself is actually a colony of innumerable tiny creatures similar to slime mould. A marshwalker is created when an entire colony comes together to travel to another location - either due to some migratory urge or to avoid some threat to their habitat.
Marshwalker capabilities
Marshwalkers are preternaturally tough. They can take punishing amounts of damage and continue moving; as long as they have access to fresh vegetation and water they can heal almost completely within a few hours from anything short of total destruction. Their powerful vitality coupled with their lack of vital organs and thick armour means it is dangerous to assume that just because a marshwalker has stopped moving, it has been defeated - their unstoppable advance is often merely slowed by weapon attacks.
Marshwalkers are monstrous creatures. Like all such creatures, they are unaffected by many spells and martial tactics (OOC note: they do not suffer the effects of combat or magical calls, although they still take damage from any blows struck to deliver them.) For example, they cannot be poisoned by conventional blade venoms nor knocked down with a polearm strike, and while arrows can wear down their reserves and cause them to retreat they do not have the devastating effectiveness they demonstrate against human-sized enemies.
Marshwalkers are mighty. Even a heavily armoured opponent can be bowled over or sent flying by one of their sweeping blows, and they can shatter a shield or pole-weapon to flinders if it gets too close. Some rare marshwalkers have been encountered that secrete poisonous slime that weakens or even occasionally paralyses opponents. In a very few rare cases, marshwalkers who have been exposed to the vallorn carry with them the miasmic taint of that corrupt environment, envenoming everyone who comes nearby.
Finally, Marshwalkers appear to be inimical to human-made structures. They can tear down minor fortifications in a matter of a few hours. They quickly smash through barricades and other hastily-erected structures designed to try and divert their migrations, and when they move through a human settlement they tend to leave damaged and collapsed buildings in their wake. There are incidents where the Druj have used groups of them to assault gates or towers; while the destruction they wreak is by no means instantaneous, it is thorough and almost irresistible.
Culture and Customs
Marshwalkers do not possess a culture. They are clearly aware of their environment, but they appear unintelligent as humans understand it. They can be cunning, and they are capable of spotting and responding to changes in their surroundings, but they do not have a language, do not speak, and appear to respond to tone of voice only. They are known to issue great echoing horn-like moans that travel great distances across the marshes - there are some reports of colonies assuming humanoid form apparently for this sole purpose. Naturalists have suggested that these serve a similar purpose to wolf howls - communicating over distance simple messages between colonies.
Primarily they are motivated by their desire to move from one place to another; to protect themselves from threats; and to smash human structures they come across. Left to their own devices, they generally collapse back into their component parts once they reach their destination or once the immediate threat (or structure) is removed.
Most of their behaviour seems motivated by basic animal-like instincts. They encrust themselves in stone and pieces of wood to form a tough shell to protect them from damage; they absorb nutrients from water, sun and plant-life to maintain their physical form; when they migrate they do so along reasonably direct routes. One strange behaviour that has caused some difficulty in the past is that, when they encounter a trod, they tend to re-orient their migration along the trod in one direction or another, allowing them to move with surprising swiftness. They rarely stay with a trod for long, unless it is leading them towards a marshy environment, but they can present an unexpected hazard to Navarr stridings.
Colonies are aware of each other and appear capable of rudimentary co-operation, although they generally fight as individuals. While they often move in a loose group, a band of marshwalkers make little attempt to come to one-another's aid during a fight.
The Druj appear to control small groups of Marshwalkers through the use of Spring ritual magic; the specifics of this magic are unclear to Imperial scholars. Marshwalkers controlled by Druj are often festooned with fetishes and similar items - especially shrunken heads and skulls. Whether this is part of the magic that controls them or simply to give them a more threatening appearance is unclear.
Marshwalkers can survive for only a few weeks away from the damp, fertile environments in which they live. Denied water or access to fresh vegetation and insects, they become brittle and begin to die. A marshwalker in this state is desperate and will stop at nothing to reach a safe location - they can inflict massive damage in their single-minded drive to find somewhere safe.
Marshwalkers in play
Due to the nondescript appearance of a colony in its placid state, a human settlement can live near an area populated by marshwalkers for decades and never realise. There are many stories of marshwalkers rising out of bogs and making straight for new construction begun too near "their" territory; smashing the structures to pieces, and pulverizing anyone who gets in their way, before returning to the marshes and disappearing.
They are very sensitive to anything that threatens their environment. For example, when the Morass in Holberg was drained the engineers required constant protection from dozens of marshwalkers who strode out of the depths of the bogs and swamps bent on destroying everyone and everything responsible for the project.
A marshwalker is a major threat to a village, and several marshwalkers might threaten a small town. A well-equipped militia can probably drive a marshwalker off, but are likely to take serious injuries in the process. A lone character can easily outpace one, and might be able to come up with a cunning way to divert one, but one-on-one will likely be quickly dispatched.
Marshwalkers are designed fill two niches. The first is an unintelligent threat that has an elemental or "natural" theme. They smash up new construction; their presence might complicate stories involving expansion of civilisation; they can even present a nasty threat to a village or bunch of travellers just by being in the wrong place at the wrong time. They're not evil, but they are implacable and dangerous and heroes may be challenged to find ways to divert them rather than simply cut them down as they cannot be sure that breaking the marshwalker apart will remove the threat of the colony that formed them.
They also fill the niche of "elemental" enemies - they have a purely natural explanation, but they incorporate themes of traditional elements and even golems. They can represent the savage face of "angry nature" without needing any sort of spiritual component - just access to a lot of mud, sticks and bits of stone from which to shape their shambling, wall-smashing bodies.
Marshlings
Smaller marshwalkers have occasionally been encountered. Little larger than human-size, they lack the immense strength of their larger cousins but tend to move faster and find it easier to pass unnoticed when they leave their marshes. They possess all the unnatural vitality of their larger cousins, but seem especially susceptible to certain types of venom which inhibits their fast-healing and fast-recovery abilities.
The reasons marshlings form, rather than a true marshwalker, are unclear but naturalists have posited three scenarios that might lead to them. The most common is that a colony is too small to produce enough mass to form a true marshwalker - the colony collapses into several smaller creatures. The less common is that a particularly large colony creates a full-strength marshwalker but there are still parts left over which puddle together to form smaller marshlings. The third explanation is that a marshwalker colony might be forced to assume the form of several marshlings by magic, emergency, or extensive damage to the primary marshwalker.
In the former case, the marshlings demonstrate "pack-like" behaviour - they are all in some sense the same creature and seem capable of fighting together to a limited degree. The latter case is even more dangerous - the smaller "satellite" marshlings protect and support the central marshwalker - again, they are all part of the same organism.
The most disturbing element of marshlings is that, even more so than full-strength marshwalkers, they tend to incorporate bits of armour and human bone into their outer carapaces. Some stories from the draining of the Morass talk about marshlings amongst the larger marshwalkers who looked a lot like they were wearing armour, with skulls and bits of banner woven into their shells - giving rise, no doubt, to further rumours of supernatural marsh spirits.
Marshlings in play
Marshlings exist for two main reasons; to offer some potential support to marshwalkers, and to make it possible for sanctioned events to have marsh monsters appear in their scenarios without needing large-sized costumes.
Marshwalker Behemoths
In theory, a sufficiently large colony could produce a marshwalker of truly exceptional size. While there are some stories from pre-Imperial times of immense creatures, none have been sighted in recorded history and they are largely assumed to be a creation of fiction.