A GM’s Guide To Rultmoork Boss Tactics [SPOILERS]

Whether you’re a new GM or an old grognard, Rultmoork is a mechanics heavy dungeon that will test your players and—if you aren’t prepared—try your patience as you read and re-read the lengthy statblocks, especially for the “boss” encounters. That’s why developer Thilo Graf graces the humble blog with this tactics guide to help the GM depict the various boss encounters of Rultmoork. Spoilers ahead!

Only GMs around? Great!

Arios the First & the Church of Still Waters

The Church of Still Waters, at first glance, might look like a particularly pitiful cult of weirdos, but there is more to them. The first consideration of the GM should be theming for the Church of Still Waters — they have deliberately designed with an eye towards two renditions. One would be to have the Church of Still Waters act as comedic relief from the bleakness of some of Rultmoork’s themes; the other would be to lean heavily into these selfsame, dark themes, use cryptic utterances and portray them as a cadre of individuals akin to what one would encounter in the Soulsborne videogames. Of course, these two can be combined, and if you have a different vision for them, go ahead!

The two most crucial pieces of information to bear in mind regarding them is that, firstly, due to their Inhumanoid Psychology, they forget all about the player characters at 11 PM. Secondly, they are immortal for as long as Rultmoork has not been cleansed of stagnation, and instinctively know this. However, the players should not realize this until they see all the cultists they eliminated suddenly greet them as if for the first time.

Regular Cultists

The regular cultists pose little challenge to the player characters, and are intended to be easily mowed down by the party; if the GM wishes for a slightly more pronounced combat challenge, using the cultist customizing options on P. 89 allows the cultist to have a slightly greater impact.

Tactics. Cultists attempt to fan out and make use of the cover provided by the ruins. They attempt to set up Arios’ Sludge Command reaction with their regular attacks. If a player character is foolish enough to approach the edge of the spire, the cultists attempt to Shove heroes off the spire, or, more strikingly, try to Grapple the heroes and jump from the spire — after all, they are immortal, and their foes are not. The cultists are utterly fearless.


Hyrkios is the bruiser of the cultists; while he won’t be able to stand his ground in fair combat against a melee-focused hero.

Tactics. However, Hyrkios does have superb maneuverability via his Ghost Legs. Ideally, Hyrkios tries to catch the party unaware with his ability to fly and maneuver in a position where he attacks spellcasters without bearing the brunt of regular attacks. If he notices a spell that requires Concentration being cast and maintained, interrupting that spell becomes his priority. He can, of course, also attempt to follow the Grapple and Shove strategies of the regular cultists.


Mer’talya can buff her fellow cultists and strike pretty hard, as her sludge is much more potent than that of her fellow cultists.

Tactics. She knows that she is the only one who can enhance the sludge of regular cultists, so she tries to stay out of melee combat when possible. She ideally tries to keep her fellow cultists within line of sight, while staying out of sight, or at least, out of the party’s reach.

Arios the First

Arios is the most pronounced challenge among the cultists, and he knows it. He’s also the guardian of a tainted tear of Vasi and attuned to it. In the likely case that the party eliminates him and loots his body, the tainted tear of Vasi will return to him at 11 PM when he revives until it is changed into an untainted tear of Vasi. If the party do manage to purify the tear of Vasi, Arios and his cultists will not remember it when they rejuvenate.

Tactics. Arios initiates combat by casting slow, or if the party is visibly under the effects of buffing magic, by casting dispel magic. A party that stays together and presents a tight formation is targeted by Stagnation Strike If he witnesses a creature being summoned or is faced with an extraplanar entity, he casts banishment to get rid of the creature. As a spellcaster, he attempts to stay out of melee, while using his Sludge Command reaction to enhance the attacks of his congregation. Arios tries to keep Hyrkios and Mer’talya in combat with his Stagnation Release reaction, while doing his best to keep out of melee with martial heroes. He uses teleport to try to outmaneuver the party. If the party seems to have preternatural knowledge of the cultist’s strategies, Arios might teleport away and use swarms of Vasi’s drops to spy on the party, summon other creatures with his rituals and prepare an ambush, provided he can do so before he “resets” at 11 PM.


One of the cool elements about the Church of Still Waters is the surprise their immortality provides when first encountered and seeing the player characters attempt to deal with that. The inability of the cultists to learn from their mistakes while they are immortal means that their strategies do not evolve to account for special tricks the heroes might employ, and if the party persists on fighting the cultists time and again, allows the GM to run a potentially hilarious Groundhog Day scenario. Of course, it’s similarly possible to run this is a way that emphasizes the existential dread of the Church of Stagnant Waters’ doctrine. Witnessing the unchanging nature and endless suffering/existence of these cultists should sooner or later drive home that their “immortality” might not be a good deal to a sane person…

The Watcher & The Listener

The Watcher & the Listener are Ylluliav’s ace in the hole, a brutal last defense to ensure that the tear of Vasi is not removed from the Dungeon of Rultmoork.
Playtests have shown that the lethality of the encounter with these two entities is highly contingent on the performance of the players prior to the boss fight, and on how well they grasped how Rultmoork’s peculiarities work. This is one of the reasons why the boss fight is so explicitly foreshadowed with not only one, but two separate read aloud texts (P. 76 & 77) once the party has taken possession of the tear of Vasi. As a GM, you are the best judge of how powerful your party of adventurers is, but here are some guidelines.

If the party has used the sacred amphora of restoration to clean the Well of Souls, or if they have not yet found it, they have a reduced capacity to quickly cure the negative conditions imposed by the two monsters; this makes the fight much harder. If the party has managed to stockpile flow tokens, the combat will be a solid challenge. However, if the party has not managed to find a sufficient amount of flow tokens and does not have the sacred amphora of restoration, the boss fight may well end in a TPK (total party kill) and needs to be handled with care.

Another aspect to bear in mind when setting up the encounter, would be the demands this boss fight has on the GM: Two complex boss monsters face the party, and the arena is potentially the entirety of the Dungeon of Rultmoork. There is a fact that makes running them much easier: They have abilities that are very similar to each other; once you’ve noticed their similarities and differences, you’ll have a much easier time running them.

Bear in mind that the Watcher & the Listener are perfectly aware of the traps in the dungeon and do not trigger it on their own. While the two monsters do not trigger traps on their own, this does not mean that a clever party can’t use the traps to their advantage.

Do remember that the Watcher & the Listener are not aware of the secret compartment beneath the statue of Vasi in Area 3-2 (P.62), nor can they open the portcullis in Area 2-4 (P.56). Both places are safe refuges if the party has to retreat.

If you are absolutely certain that the Watcher & the Listener are too much for the party to handle, split them up. This strips them of their most powerful ability, Deadly Deprivation (P.102).

Regardless of how you want to run the encounter, be sure to show the players the artworks as you read the descriptions; the artworks are deliberately this grotesque and contain visual hints (like the Watcher’s Motes of Current) on how to tackle them.

The Watcher

The Watcher is the more agile of the duo and knows that its blinding abilities do not have the same area of effect capability as the deafening abilities of the Listener. As such, it prefers targeting spellcasters and ranged combatants, such as characters wielding a bow. When you depict the Watcher, point your hands at the targeted players when using Eye-Fingers, and when using I Can See You, point both hands at the player of the target.

Tactics. The Watcher begins combat by using Eye-Fingers on two characters that look like spellcasters or ranged combatants. Whenever possible, it cooperates with the Listener to use Deadly Deprivation; since the Listener’s Tympanic Pulse has a higher chance of affecting a character due to being an area of effect assault, the Watcher is the more likely creature to combo a player character into this state. If the Watcher fails to blind a potent adversary, it uses I Can See You on that target. If it notices a character using flow tokens or similar effects that might trigger Flow Metasis, it targets the offending character. It only uses By Duty Charged if has lost half or more of its hit points. It’s excellent Dexterity and Medium size means that it is harder to lock down than the more cumbersome Listener. If locking the party down in Deadly Deprivation does not work or the Listener falls, it starts using its reaction for Conduct Current instead.

Hardcore Mode.

The Watcher is a puzzle in disguise that rewards player skill and tactics. If you want to emphasize how deadly these monsters are and your party enjoys challenges that focus on player skill, use one or more of these options.

No Save for Eye-Fingers. The Watcher’s Eye-Fingers have two chances to avoid them: They require an attack roll to hit, and also offer a saving throw to negate the blinded condition. As such, if you want to, you can remove one of these safety nets; eliminate the saving throw on a hit, but not the saving throw to shake off the condition. This results in an almost guaranteed Deadly Deprivation in the first round of combat.

Permanent Blindness for I Can See You. By stripping this attack of the option to shake off the blinded condition, you can significantly increase how deadly the encounter is. In this instance, any effect that would change a creature into flow mode should also be able to cure this form of blindness. Since the Listener’s Clicking Claws cause permanent deafening, this can quickly lock down targets.

/Hardcore Mode.

The Listener

The Listener is the brawler and blocker of the duo. Courtesy of its large size, it can control a larger area, but also becomes slightly easier to attack. The Listener knows that its abilities, while less debilitating than those of the Watcher, have a higher likelihood of affecting a character, and as such, it tries to set up as many deafened creatures as possible for the eventual Deadly Deprivation combo.

Tactics. The Listener initiates combat by using its Tympanic Pulse to deafen as many targets as possible, and then wades into melee. Due to its unique way of “seeing” creatures with its Sonar Clack, it is possible to outmaneuver the Listener by making clever use of the dungeon. Since its Clicking Claw’s deafening effect has no save to resist (its slimy earwax flows into the target’s ears…) and it knows this, the Listener tries wading into melee and target the burliest-looking characters. As with the Watcher, it tries to keep its reaction to potentially set up Deadly Deprivation whenever possible. It uses Echo of Duty only once it has lost half or more of its hit points. If locking the party down in Deadly Deprivation does not work or the Watcher falls, it starts using its reaction for Resonance Rupture instead. The Listener has a significantly higher chance to successfully use End Silence than the Watcher has to use Sight Recovery; thus, if the Watcher is blinded, and the Listener deafened, it tries supporting its partner as soon as possible once it has recovered its bearing.

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Ylluliav Vleckmar

The corrupted high priestess of Vasi is easily the most deadly adversary in all of Rultmoork, and has a plethora of options available at her behest. An important aspect of her theme as the lynchpin of stagnation in Rultmoork, is that she doesn’t need to move on her own: She uses her ability to levitate and rather breaks reality with I Am Rultmoork, Forevermore than move in a conventional way.

The key to understanding Ylluliav, is to be aware of her two resources: The first and most important one, is her Veil of Stagnant Waters. All her best abilities require that she expends the charge of her veil. The second is that, if she does not have her veil’s charge or wants to conserve the charge, she attacks with her slimy Tainted Amphora of Stagnation, which encompasses all the attack options listed on P. 109.

It is important to bear in mind that Ylluliav cannot use her Tainted Amphora of Stagnation after using her I Am Rultmoork, Forevermore…unless she spends her lair action to recharge the amphora.

Her tactics change, based on where she is encountered, but there are some commonalities:

General Tactics. Ylluliav is a spellcaster, and as such, she attempts to stay out of melee range—nothing kills a spellcaster faster than half an adventuring party whittling away at them. Thus, she levitates out of earth-bound melee-range immediately. She also knows that she has infinite minions, at her disposal, and as such, only needs to outlast the adventurers. If the party seems to be buffed by several magical effects, the levitating Ylluliav starts off combat with dispel magic. Her first round’s legendary actions will be Painless Eternity (consuming the veil’s charge), followed by a use of her Tainted Amphora of Stagnation. Her lair action, unsurprisingly, defaults to calling her minions with Vasi’s Dead or Stagnant Guardians, respectively. While she’s out of the adventurers’ reach and combat seems to be going her way, she uses Command Retaliation to enhance her minions.

On subsequent rounds, she’ll use two of her legendary actions to recharge her Veil of Stagnant Waters if she doesn’t make the recharge roll, or if she wants to have the charge available for an emergency.

Since her Veil Strike is her best direct attack option, and has a reach of 20 ft., she can remain out of melee reach and even behind her minions and still attack. As this attack consumes her veil’s charge, she won’t use it when in danger of being surrounded or targeted by several characters in melee.

Ylluliav’s most powerful defensive option is her I Am Rultmoork, Forevermore reaction, as it allows her to avoid being surrounded by the party or targeted by too many melee-focused characters. However, it also strips her of her regular attack options and depletes her veil’s charge, putting her in a more defensive position during the next round. Ylluliav can use the Replenish Amphora lair action to use her amphora in spite of this limitation, but this also prevents her from using her other lair actions.

After using I Am Rultmoork, Forevermore, Ylluliav tries healing herself if she has been reduced to half her hit points or less at the earliest convenience; if she is not severely injured, does not have her veil and wants to conserve her lair action, she can use her spellcasting to pester the party, particularly the slow spell.

If Ylluliav has minions in play and is sorely pressed, she can use all her legendary actions and her veil’s charge to use Armor of Stagnation; while this ability does not allow her much hope to deal with ongoing effects, time is in Ylluliav’s favor, and the armor allows her to focus on debuffing and calling more minions. This is essentially a last resort that allows her to recover her footing.

Well of Souls Tactics. In the Well of Souls, Ylluliav has a very deadly lair action with Flood of Muck; this is an area of effect attack that can push characters into the deadly Pit of Sinking, Stagnant Skulls (P.74); there is a good chance that use of this ability manages to occupy more than one hero on their turns, so Ylluliav utilizes it to break up the party’s formation and target as many characters as she can.

Great Clepsydra Tactics. In the Great Clepsydra, Ylluliav has more powerful, but less numerous minions, which makes her Command Retaliation reaction stronger. Additionally, her Cocoon of Stagnant Waters allows her to gain a shield of sorts and get more easily rid of negative conditions; Following Armor of Stagnation with a recharged veil and a Cocoon of Stagnant Waters allows her to potentially recover from the very brink of defeat. If you are using the Puzzle Combat option for the finale in the Great Clepsydra, do remember that Ylluliav can attempt to stop characters approaching the cistern with a combination of I Am Rultmoork, Forevermore to get into position, followed by Armor of Stagnation as a last-ditch effort to stop the party.

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