Also, no blue or purple Tieflings

But then we all know that the Player’s Handbook, p.42 disagrees… as does the Sword Coast Adventurer’s guide, p. 118 for the not so small fraction playing in Faerûn or some world derived from it.

Seduction is RAW, it’s called Persuasion (or Deception) and likely has a high DC.

DM should re-read the rules since a description of a dragonborn in the rules state they mostly do not have tails, but there are exceptions as well as the fact that “seducing” someone would be a deception or persuasion check as if I said “I lie to the guards” isn’t me trying to use a skill called “lying.”