Werebeasts, a.k.a. lycanthropes, are wonderful enemies. A werebeast encounter can be awesome action or tragic drama. Werebeasts lend themselves perfectly to horror-mystery adventures, in which the players have no idea which of the villagers is the true villain. They threaten to transmit their lycanthropic curse to any character who fights them hand-to-hand—monsters who can make the player characters into monsters themselves. Practically by definition, werebeast encounters take place at night, when everything is scarier. And if the werewolf ever seems too clichéd an enemy, werebeasts come in four other varieties.
All werebeasts have proficiency in Perception and immunity to physical damage from nonmagical, nonsilvered weapons. They also have human forms, beast forms and hybrid forms; their human forms are their “true” forms. My sense as a dungeon master is that they take their beast forms to run around and hunt in the wild, but among people, they take their hybrid forms when their curse is upon them—at any rate, the hybrid form makes for more interesting and challenging combat encounters than the beast form, because it allows them to use their Multiattack action feature. (The exception to this pattern is the werebear, which has Multiattack in all its forms.) But if you want to conceal the fact that the PCs are fighting a lycanthrope and not simply a big, ferocious beast, you may opt for the beast form after all, trading a reduction in damage for the increase in likelihood that the PCs will carelessly let themselves fall afoul of the lycanthropic curse.
Although the Shapechanger feature, common to all werebeasts, states that they can use an action to polymorph from one form to another, I’d disregard this, for two reasons. First, there’s generally no advantage to it: any equipment they’re carrying isn’t transformed, so, for example, a humanoid wearing armor and carrying a sword turns into a beast standing in a pile of armor and staring at a sword on the ground; or a hybrid with natural armor turns into a naked, unarmored, unarmed humanoid. Meanwhile, it’s just spent a whole combat round transforming when it could have been, I don’t know, attacking or running away? And second, isn’t the whole point of lycanthropy that the afflicted individual has little or no control over his or her transformations? High opportunity cost, no obvious benefit, contradicts werebeast lore: there’s only one logical situation in which to use this action, and that’s at nightfall or daybreak, when the lycanthrope changes involuntarily.
Werewolves in their hybrid form lack any ranged attack, so they’re strictly melee fighters. They possess proficiency in Stealth, so they’ll strongly prefer attacking from hiding, with surprise. They have Keen Hearing and Smell, which gives them advantage on Wisdom (Perception) checks using these senses, but this doesn’t negate disadvantage from attacking in darkness, since they lack darkvision. Their immunity to normal weapons makes them unafraid of opportunity attacks, generally speaking, and as predators, they’ll prefer easy prey to hard prey. Consequently, they’ll attack the weakest first (in a village, that will mean commoners, not seasoned adventurers), and if struck by a ranged weapon attack or a spell attack, they’ll immediately Dash (action) out of sight, thereafter to Hide (action) again and resume stalking prey. However, if a PC aims a melee attack at a werewolf and either misses or does no damage or insignificant damage (5 hp or less), the werewolf will counterattack against that PC, clawing and biting. A werewolf struck by a magical or silvered weapon, either melee or ranged, will flee, using the Dash action.
Werewolves in their hybrid form can speak and understand speech, but they generally don’t have much to say. When slain, they return to human form, and I like to use this moment to deliver the players an extra punch in the feels—for instance, by having a group of three slain werewolves revert to the forms of two young women and a teenage boy, who all bear a strong family resemblance to one another.
Werewolves are most likely to be found in small country villages; wererats are urban creatures. Since wererats’ Strength is lower than their Dexterity and Constitution, and since rats are naturally social animals, wererats will congregate in gangs and favor skirmish fighting over crude brawling. They’ll attack victims whom they outnumber at least two to one, sniping with their hand crossbows from hiding, from behind cover and from multiple directions. Their overall strategy is to wear down, then close in when all their victims are seriously wounded (reduced to 40 percent of their maximum hit points or fewer). If a wererat’s target charges and engages it in melee, it will fight back fearlessly with its shortsword and its teeth, unless and until it’s struck by a magical or silvered weapon or a spell attack. In that case, it will Dash (action) into the shadows. Once other wererats realize that their fellows are being driven off by magical attacks or silver weapons, they too will break off attack and withdraw.
That’s not necessarily the end of it, though. The PCs may decide to give chase—at night, through the streets and alleys and shadows, which means that while fortune may have turned momentarily against the wererats, they still have the home field advantage. They’ll scatter, but they won’t go far, and once one has found an advantageous hiding place, it will Ready an Attack action, shooting a crossbow bolt at any PC who passes before it—if there are multiple targets, favoring the ones carrying the magic or silvered weapons or casting the injurious spells. On its next turn, it will slip out of sight and hide again. This will continue until the PCs kill all the wererats or give up pursuit. And woe to the PCs if they split up: the wererats will quickly figure out which group is the smallest and weakest and converge on it.
Slain wererats often revert to the form of piteous street urchins. The feels! Right in the feels!
Boars are also social animals, so wereboars will also attack in gangs, and like werewolves, they range primarily in the country rather than the city. They’re brute attackers with no skill at stealth; they initiate combat with a Charge, followed by a tusk/maul Multiattack. The tusk attack comes first, because it may knock the target prone, giving the wereboar advantage on the subsequent maul attack. If a wereboar’s opponent tries to retreat, it presses, Charging if the opponent is at least 15 feet away; if it knocks an opponent unconscious, it Charges the next one.
Wereboars are tough and stubborn—their Relentless feature keeps them going even when they’re reduced to 0 hp—but that doesn’t mean they like being struck by magical or silvered weapons. They’ll retreat after being moderately injured (reduced to 54 hp or fewer) by either of these types of weapon or seriously injured (reduced to 31 hp or fewer) by spells. Their version of retreating, however, isn’t to Dodge, Dash or Disengage but rather to deliver a parting Multiattack action before backing off at full movement speed, without concern for any opportunity attack this may incur.
Tigers are “solitary but social” animals: they hunt separately, but a group of female tigers may lair together. (Male tigers both hunt and lair alone.) Therefore, an encounter with a weretiger will always involve a single individual, unless the party has stumbled upon a lair belonging to a group of females or a female with offspring. Even so, this group won’t be large.
Weretigers keep to remote areas and generally don’t hunt humanoids; any that does is an exception to the rule, and this may be why the PCs are fighting it in the first place. It would also be a reasonable justification for having the weretiger fight in hybrid form, since according to the MM flavor text, weretigers generally prefer to keep to human form; using the hybrid form will highlight its deviant nature.
Weretigers have darkvision in all their forms and proficiency in Stealth, so these are nocturnal ambush hunters. Their Pounce feature is similar to a Charge but with the addition of a bonus bite attack. They can wield longbows, but I think this is something that ordinary weretigers would use to defend their territory; a rogue weretiger would favor the potent melee combo offered by the Pounce feature.
Therefore, the rogue weretiger (not to be confused with a weretiger rogue!) stalks its prey from hiding, then Pounces with surprise. What does it consider prey? Probably not a whole party of well-armed adventurers—but then again, weretigers have only average intelligence, so they may underestimate a group of PCs. Still, while a weretiger won’t hesitate to attack a single PC and probably wouldn’t balk at two, a group of three, four or five is another matter: they’d have to be weak, or at least weakened, or the weretiger would have to possess some sort of situational advantage, beyond mere darkness. It won’t touch a group of six or more, period.
Using the Pounce action in its surprise round, the weretiger gets 15 to 30 feet of movement, a Multiattack action comprising two claw attacks, and a bite attack as a bonus action. After that, is there any reason for the weretiger to bother drawing a scimitar and slashing away? Nah. As long as it’s engaged in melee, it will continue to use its claw/claw Multiattack.
Like other werebeasts, weretigers know that magical and silvered weapons can hurt or kill them, as can spells, and they’ll withdraw quickly when moderately injured (reduced to 84 of fewer hp), because anything that can deal a moderate wound to a weretiger can probably do worse as well. It will Dash (action) away, then Hide (action) as soon as the PCs lose sight of it. But as with wererats, the encounter probably won’t end there, because the PCs will have been hunting the weretiger in the first place. As much as it can, it will use Stealth to avoid them and will fight back only against a single PC if the party splits up.
But suppose it’s not a rogue weretiger we’re talking about—suppose it’s a regular, I-just-wanna-be-left-alone weretiger that the PCs are hunting? According to the MM flavor text, this kind of weretiger will prefer to keep to its humanoid form whenever it can, and in that form, it will prefer to hide and not be found. It won’t even counterattack from hiding with its bow, because that would give away its position. It simply hides and stays hidden until the PCs go away. If the PCs get too close—say, within bowshot range—this is the rare instance in which it makes sense for the weretiger to Shapechange from humanoid to tiger form, because in this form, it has a movement speed of 40 feet and thus can more easily run away. Only when defending its lair will it stand and fight, with its scimitar; and in this instance, it will fight to the death, because it knows that if it doesn’t prevail, it will most likely be killed.
Werebears are good creatures and solitary, and they really want to be left alone. If the PCs have a violent encounter with a werebear, it’s because they’re trespassing in its home and refusing to leave, or they’re evil characters who are hunting the werebear. Either way, it’s a ferocious melee fighter, making two mighty greataxe attacks per turn in its daytime humanoid form and two even mightier claw attacks per turn in its nighttime hybrid or beast form. With 135 hp and immunity to damage from normal, nonsilvered weapons, the werebear takes no guff. And even if you can hurt it, while it might flee when injured in the wild (say, upon being reduced to 94 hp or fewer), it will fight to the death when defending its lair. “Leave! Me! Alone!”
One thing the werebear generally won’t do is bite. This is partly because, according to the MM flavor text, werebears prefer not to transmit their lycanthropy to others, but it’s also because the werebear’s Multiattack doesn’t include a bite. A single bite is simply less effective overall than claw/claw.