Baphomet in Way of the Wicked (WoTW / WoTR spoilers)

Personally, I can't really see the Templars having much of an involvement in the events of the first book. If you want them to play a role, you could have Hosila (human inquisitor 3), Faxon (tiefling witch 4), or Derandau (fiendish minotaur) as prisoners of either Brandescar or in Thorn's basement during the Nine Lessons. Obviously, in the latter case they would be in different rooms then Timeon and Sir Balin.

In this book, the villains take over the Horn of Abaddon and maintain their hold on it for seven months to summon the daemon Vetra-Kali and acquire the Tears of Achlys. But the Templars desire this power as well. Nurah Dendiwhar, the traitorous level 8 halfing bard from Wrath of the Righteous' second book might be featured here. She may approach the party in Farholde and offer her services. However, she is a minion of the Templars who sets to inform them of the Nessian Knots' activities and help them seize the Horn for themselves. How the party deals with her is up to them: they could have her horrifically tortured, slain, and strung up in Farholde as a warning to the other Templars, they could attempt to cajole her into joining Asmodeus' side, or feed her false information as a kind of counterintelligence effort against the Templars.

Needless to say, seven months is a long time for Baphomet's followers to intervene directly. When they attempt to invade the Horn, their forces could consist of half-fiend minotaurs, assorted demons, and mortal followers. Wrath of the Righteous' third book, "Demon's Heresy" provides statistics for other Templar-aligned NPCs as well: antipaladins of Baphomet, Blackfire adepts, a tenth level summoner named Zanedra and her eidolon, a mythic glabrezu disguised as an elven woman named Jerribeth (CR 14/MR 2), and a worm that walks named Xanthir Vang.

Jerribeth is only one CR-point higher then Argossian the silver dragon, so she might make a good enemy to attack the Horn during the last few days of the ceremony. But having too many allies fighting alongside her may swing the battle too far in the Templar's favor. Perhaps she merely waits out in the Caer Byr and observes the Nessian Knot from a distance.

The primary objective of the PCs in this book is to lead an army to take over the Vale of Valtaerna, slaughtering the Order of Saint Macarius. This is an objective that the Asmodean Knots share with the Ivory Templars, so they would most likely not interfere with the PCs' war effort. Perhaps the Templars have entrenched themselves Ghastenhall's Red Quarter, and are developing a network of contacts there. Barnabus Thrane could inform the PCs of the Templar's presence in Ghastenhall, leading to the party embarking on brutal urban search-and-destroy missions to thin the ranks of Baphomet's followers. You could even put the Ivory Sanctum from Demon's Heresy in Ghastenhall, and have Xanthir Vang as a boss encounter (with the minor plot alteration if him being a servant of Baphomet as opposed to Deskari).

In this installment, the party aids in the sack of Daveryn, enlist the aid of the black dragon Chargammon, slay the copper dragon Eiramathus, and finally infiltrate the palace of Adarium to slay Talingarde's king. There are a few opportunities to add the Templars' machinations here. You could have some of their elements still be present in Daveryn. The presence of a few minotaurs amongst Sakkarot's vast army of bestial savages would probably not attack that much attention, allowing them to spread Baphomet's doctrine from within Sakkarot's ranks. This must be stopped. Another thing that the Templars could be doing in this city is trying to recruit or assassinate Baroness Vanya. If the PCs consider her an ally, they will have to hurry and put a stop to this.

Thematically speaking, it might be cool to have the Templars have already sought out Chargammon's assistance. Now, their half-eaten corpses are strewn across the floor of his cave for their insolence.

Since Matharyn is such a piously good-aligned city, both the Templars and the followers of Asmodeus probably have very little influence there. This can be changed in time, but during the immediate objective of invading the palace, it is not all that relevant.

It is possible that Minagho, a Lilitu servant of Baphomet, has infiltrated the Adarium with the intent of murdering Bellinda and using her husk as a disguise to rule Talingarde. Given the CR different between them, she's unlikely to succeed in this endeavor, but she may come across the PCs. Alternatively, she may have successfully done this to High Cardinal Vitallian of Estyllis, the head of Mitra's church in Talingarde. By assuming his husk, she can undermine the faith of Mitra and increase the Templar's power across the land, adding a layer of intrigue to the campaign.

When book five rolls around, Baphomet's efforts in Talingarde become multi-pronged, elaborate, and vicious. The specific methods used by the Templars of the Ivory Labyrinth to retaliate against the party will be detailed as follows:

*Shortly after the massacre of King Markadian's army at Daveryn, Sakkarot is discreetly visited by Hepzamirah, the half-nephilim daughter of Baphomet and the leader of his cultists on the material plane. She wishes to persuade him to leave Asmodeus' side and join the Templar's ranks, bringing his entire army with him. Sakkarot reluctantly informs her of Thorn's plot to have him betray his army to slaughter at the hands of the PCs (see: Book four, act one, event two) and that he will serve as Thorn's servant afterwards. In response, Hepzamirah offers him a deal: agents of Baphomet will infiltrate Hell to burn his contract (see: contract devil description) and that he will subsequent defect to Baphomet's faith. He is frightened by the concept of betraying Cardinal Thorn but says that he'll consider it. Whether or not he joins the Templars is up to the party.

*Seeing as how the diabolist faction is split between the Nessian Knot and it's followers against Thorn and his minions, Baphomet senses weakness in the enemy's ranks and escalates his efforts against the party. This could take the form of demons attacking them, or some other hostile action on Baphomet's part.

*If Sir Richard Havelyn is not killed or corrupted by the party, the Templars of the Ivory Labyrinth will attempt to turn him to their side. He becomes an antipaladin of Baphomet capable of smiting Asmodeus' followers. Havenlyn is ready for battle by the time the next book begins.

*It's possible that Hepzamirah and the other Templars have found out about Thorn's phylactery located in Nithoggr's hoard, either through divination or some other means. In that case, Hepzamirah arrives with a powerful retinue at about the same time the party does. There might be a three way battle between the PCs, the Templars, and Nythoggr. Or the Templars may succeed in taking the phylactery and fleeing. They might even take it back to Baphomet's abyssal realm of the Ivory Labyrinth, which would cause no small amount of complications for both the party and Cardinal Thorn.

*When the PCs travel to the Agathium in the north to confront Cardinal Thorn for the final time, Baphomet is watching. He attempts to have his agents contact Sherkov, Ingolfr Issox, and any others in the Agathium that he might be able to convert to his side. But mainly, Baphomet waits for the party to fight and slay Thorn. Shortly afterwords, a demonic death-squad led by Hepzamirah (or some other powerful demon, if she is dead) arrives and ambushes the PCs, hoping to overwhelm and kill them after they've been weakened by battles throughout the Agathium. At CR 19 and backed up by powerful minions, Hepzamirah should at least be partially challenging, especially in the party's current state. If this attempt fails, Baphomet is truly enraged…

In the final book of the adventure path, Baphomet embarks on all-out war against Asmodeus' followers. If Sakkarot has decided to betray the party, he now attempts to do so, jeopardizing their plan to assume rulership of Talingarde. The bugbear warlord's alignment changes from lawful evil to chaotic evil, and he now reveres the Horned Lord as his master. As a reward for his service, Baphomet bestows the half-balor template (Demons Revisited) upon him, increasing his CR by 4. The party has no choice but to kill him. In addition, the Templars have placed agents through Cedrick Malthus' mercenary army. It's possible that entire companies of them are loyal to Baphomet! How the PCs deal with this is up to them, but if left unchecked this hidden cells may become a problem.

After the party formally takes over Talingarde, the Templars of the Ivory Labyrinth probably fade into the background. But three months into the PC's reign, a pair of Mariliths and their Glabrezu slaves teleport into the palace and attempt to slay the PCs at Baphomet's behest (this actual occurs in the module, but the demon lord that sent them is not named). After dealing with this incursion, they are contacted by the pit fiend Naburus, who announces that Baphomet has captured Basileus, herald of Asmodeus. The lord of minotaurs intends to twist and corrupt Basileus into his own herald. This insult must be avenged!

At this point, the adventure uses the content of Wrath of the Righteous' fifth book, "Herald of the Ivory Labyrinth", albeit modified. There is no encounter with Iomedae, and the PCs are evil characters. Basileus, if he is corrupted, uses a heavily modified statblock. The Nessian knot fights through the Ivory Labyrinth and confronts Baphomet in his Ineluctable Prison, facing off against him in a climatic showdown. The only quandary here is the rule that demon lords must be killed twice, but I'm fairly certain that skilled GMs can navigate around that. In any case, the Horned Lord suffers greatly for his defiance of Hell. Now all that remains in the path of the Nessian Knot's dominance is Bellinda and her army...