What are some traps for a dungeon that wont do crazy damage?

@8bitsweater @ChrisPerkinsDnD @Wizards_DnDwhat are some traps for a dungeon that wont do crazy damage to my players and make them think? maybe more of a puzzle? code or riddle needed to open a door? #wotcstaff

— Mike Mearls (@mikemearls) March 10, 2017