Variant Rule: Monster Information

Whenever players wish to know what if their characters know something about a monster (especially monsters they have not encountered before), they may make a knowledge-based d20 skill check to see what (if anything) their character knows. The DC for this skill check is equal to 10 + the creature's challenge rating (minimum 11). Which skill the check uses is determined by the GM based on the creature type. This check may not be repeated.
Success will means the character knows what the monster is (they are told the monster name), and allows the player to ask 1 question about the monster which their character is assumed to know. Exceeding the DC by 5 or more permits the player to ask 2 questions, and exceeding it by 10 or more allows them to ask 3. It is up to the GM to determine what constitutes a valid question, and suggest alternatives if a question is rejected for being to broad, vague, etc.
Example questions and Result:

• Does the monster have any resistances?
  The player is told what resistances the monster has (if any).


• What is the monsters highest (or lowest) save?
  The player is told the monsters highest or lowest save (but not what the bonus is).


• What languages can the monster understand?
  The player is told what languages (if any) the monster understands.

Note: For learning about monsters through research, see the Downtime Activities in Xanathar's Guide to Everything.