Sealers are heralds who have dedicated themselves to keeping powerful malevolent forces at bay. They willingly put themselves on the front lines of the battles against otherworldly horrors, powerful dark lords, marauding dragons, evil divine forces, and other threats that often cannot be destroyed, but must be contained for the good of the world (such as the legendary Tarrasque). The first Sealers were sinuous, but they are spread across every sapient people in the world now. Because of this important work, they tend to not spend a lot of time seeking out lesser concerns to trouble themselves with; a Sealer will be as motivated to stop a slaughter or kidnapping as anyone, but they generally don’t much care about notions of purity or piety.
Sealers like to work with more powerful spellcasters such as wizards and clerics to contain the entities they fight, and the most powerful of them can draw upon some of the very same magics these dedicated spellcasters use.
All sealers hold similar tenets, regardless of any master they serve.
Add the negation school of magic to your list of herald spells.
At 3rd level, you gain proficiency with the Arcana and Religion skills. If you are already proficient, you gain an expertise die instead. You also gain proficiency with the Sanctified Steel combat tradition.
Also at 3rd level, as a bonus action you can spend 3 points from your Lay on Hands pool to create a vial of holy water or a bag of holy salt. Items you make in this way are extremely unstable and must be used immediately. If an item you created in this way is not used (thrown, sprinkled, or applied as appropriate to the item) by the end of your next turn it dissolves into useless sludge.
You can use this feature to create a number of items equal to your proficiency bonus. You regain all expended uses when you finish a short or long rest . You cannot regain expended uses in this way if you don’t have access to tools of artifice.
At 7th level, your training seals your mind against supernatural manipulation. Your thoughts cannot be read unless you consciously permit it, and you have advantage on saving throws against spells and effects that would cause you to become charmed, confused, frightened, or compelled to perform specific actions.
At 15th level, you gain access to powerful sealing magicks. You can cast the forbiddance, guards & wards, and symbol spells once (each) per long rest. In addition, private sanctum is added to the herald list for you.
Finally, you always have the counterspell, dispel magic, and remove curse spells prepared (they do not count against your limit of prepared spells).
At 20th level you learn the most powerful ability of the sealers: once per long rest you can cast imprisonment as a ritual.