For OSR Adventures
 Door bursts into flames and explodes outwards. Person who opened door takes 2d6 fire damage, save for half. Everyone nearby takes 1d6 fire damage, save to avoid.
 Door animates and wraps itself around person who opened the door. It crawls on them like a monkey, resisting all action to get it off. Encumbers as plate armor, or 2 standard carrying units. This could be burned off, but burns the person who the door is attached to as well. Once you return to town a carpenter can make a nice doorframe as a new home for the door to lift the curse safely.
 Poison gas released. Everyone nearby the door saves or takes 1d6 poison damage over the next few turns, 1 damage per exploration turn.
 Thick door frame was actually hollow, filled with Big Centipedes.
 Metal ball on chain punches through doorway, deals 1d8 damage. If you have a shield you can absorb the hit with the shield but the shield gets damaged.
 Blade hidden within planks or doorframe. Save or take 1d6 damage.
 Bells and chimes hidden nearby, make noise. Roll for a random encounter.
 Door becomes splotchy and moldly, crumbling to dust. The person who opened the door is cursed by a corrupted power, making them have -1 to all saves until they plant 10 trees or help in the harvest.
 All light sources are snuffed out, including magical ones. You're trapped in unnatural darkness for 1d6 turns. The following room was sanctified to the Gods of the Dark, hence the darkness trap.
 The person who opened the door has their skin turn the color of wood. They take 1d10 Dexterity damage, save for half. Goes away slowly over time or by having sex with a lumberjack.
 Door rips in half, its hinges become the joints in the jaws of its new mouth, made by folding half the door on top of itself and animating like a giant snapping set of dentures. Door Maw.
Big Centipedes (1 HD, +1 to hit, bite d4 damage, can crawl up walls and pants)
Number Appearing; 1d4+1
Door Maw (2 HD, +2 AC, weak to fire, wide bite deals 1d6 damage to 2 adjacent targets)
Number Appearing; 1