Blessing of the Dragon's Mark (5e Blessing)
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Blessing of the Dragon's Mark
Making dragons non-hostile in Dungeons & DRAGONS! What's not to love?
You've been marked as under the protection of a powerful dragon, such as a deity or Prismatic Dragon. To your character, it might seem like a mutual bond of friendship or something, but let's be honest, it probably actually tells others you're owned by the guy.
Any dragon-type creature that sees the mark (or smells it, though only they can) understands that you've found the favor of it's creator. Dragons that know this will refuse to fight you willingly, even if you turn hostile to them. They might use other means to avoid having to injure or kill you without you interfering with their plans, such as trickery or spells that place you somewhere else (Like a forced Plane Shift, but keep in mind it would always send the marked creature to somewhere safe for them, since it's actively trying to avoid injuring them). Additionally, dragons that are the same basic alignment as you (Ignoring chaotic, neutral, and lawful) will be more willing to help you in your endeavors. This might be because you've proven yourself to a powerful dragon as someone worth trusting, or it might be because they'd seek favor with such a dragon. The mark harbors a message of the DM's choosing in the visual and olfactory details of its make, which only dragons can understand without magic (An Identify spell also shows the message) and is usually linked with the reason why dragons are willing to help you.
Other creatures can see the mark and understand what it is, though without understanding the message within. Beasts, Monstrosities, and Plants with a CR equal to or less than your level act as if charmed by you if you act friendly to them. If you turn hostile to them, they act as if frightened. These charmed and frightened effects will occur even if the creature is otherwise immune to them, but only if the creature has an Intelligence score of 5 or less (I.E., is nonsentient. The DM can decide that sentience works differently in their campaign, changing this parameter appropriately.) The charm effect does not make creatures understand you that wouldn't otherwise, but they'll be able to tell if you mean them harm or not, and will avoid fighting you if you don't. A creature frightened this way will always flee if it thinks it can escape.
In addition, other powerful creatures might understand the mark (Though not its message), and be less willing to fight the marked creature at the DM's discretion, though they aren't bound to remain hospitable if the marked creature turns hostile or earns the creature's wrath.
Finally, creatures that are enemies of the dragon that marked you will invariably be hostile towards you if they realize you have it. They might attack on sight, plot in the dark to get rid of you, or otherwise manipulate your situation in negative ways to make your life as miserable as possible.
(DM Note: The wording on this might need some work, but I wanted to make it right now before I played tonight. You can improve the wording if you want, and I'll try to do so later, but without changing its base effects.)