This is one of the many encounter cards for our boardgame Ponyville Mystery, an investigation encounter card to be specific. You draw one of these cards randomly if you end your turn on an Investigation location. There are a total of 8 Investigation locations, each one with its own color code. If one of the colors matches the one on the card, you've found your encounter, if not you'll draw again until you do.
Green cards (like this one) have special encounters for the Castle of the Royal Pony Sisters (full of traps and mysteries!), the Caves beneath Canterlot (mysterious and long forgotten), Tartarus (is Cerberus watching?) and the Realm of Dreams (maybe Luna watches over you?).
This card in particular has special encounters for the Castle of the Royal Pony Sisters, the Tartarus and a general encounter for all of the locations above not getting a special one this time.
See the backside of the card here:
Daily card challenge: Day 41