Ambition of His'tuun is an aberration created with the sole intent of pushing creatures to want more, and to want to be more. His'tuun demands more worshippers, and Ambition is all too happy to deliver in the form of the Aspirants.
Ambition of His'tuun is a fairly straight forward fight, but potentially deadly. Each Ambition is likely to have an Aspirant or two with them at all times, but what about other followers of His'tuun? Perhaps you sprinkle in a Devotion or Conviction as well.
Mechanically, Ambition attempts to bring creatures to it with Alluring Scent. If a creature takes the bait, Ambition sets upon the creature and begins converting it immediately. If engaged directly in combat, Ambition will stay as far away as possible and simply use its Acid Spit ability while goading the Aspirants to engage directly.
Aspirants are very single minded as well, they have one thought: convert. No matter the danger to them, if they sense a being they can infest, an Aspirant will rush that target. If they reach a target, they'll use Knock Out. The second they can use One Of Us, they will do so.
Neither Ambitions of His'tuun nor His'tuun Aspirants have much of a personality, being very single minded. They serve His'tuun and are devout to the purpose they were created for.
With One of Us, the creature is fully converted and cannot be brought back. They will behave exactly like another His'tuun Aspirant.
Devotion of His'tuun was created into this plane. Willed, almost. His'tuun needs its competitors removed, and that can only be done with Conviction.
With Ambition of His'tuun, there are two real parts - investigation and combat. During investigation, a heavily unsettling theme is best. The Sanctuary from Children of Morta is plenty off putting for this.
During combat, Ambition and Aspirants are not massive threats unless there's a lot of them. Tesham Mutna from The Witcher 3: Blood and Wine worked well for Devotion, and it will work well here too!
