The DM may introduce special kinds of doors that follow alternate rules, but the following are good standards:
It's an often missed rule that all dungeon doors are difficult for PCs to open, and easy for the dungeon's denizens to open. It's important to read all the dungeon door rules, which are found on DMG 97. All dungeon doors MUST be rolled for in order to open. Up to 3 characters can try to open a door in one check. Obviously, 2 or 3 characters gives a better chance to open the door than 1 character.
Any character who assisted in opening the door is in the room or corridor beyond afterward.Ex1)
A failure to open the door means anything beyond the door is alerted to the attempt and cannot be surprised by the opening party. Additionally, a wandering monster check is triggered for each failure.
Door checks can be made indefinitely until they succeed, keeping in mind the above downsides.
Dungeon doors always close at the end of the following round unless a character spends the round holding it open, during which time they cannot fight, cast spells, etc. Dungeon doors will also stay open if a monster wants it to stay open.Ex2)
There are no official rules for this. The following system is suggested:Ex
Spiking doors takes round per spike and makes noise, triggering a wandering monster roll for every spike. Spikes are not recoverable. A monster can remove spikes instantly, effectively ignoring them and operating the door normally, regardless of the monster's size.
Rolls are made privately by the DM, similar to turning duration rolls.
There are no official rules for this. The following system is recommended:Ex
Dropping items can trigger saving throws, especially if they are ceramic or glass. Dropping a torch has a 1-in-6 chance for the torch to be extinguished. Dropping a lit lantern has a 5-in-6 chance to ignite the oil as though a lit flask of oil hit the point of impact.
Falling damage is 1d6 points per 10’, not cumulative.3)
The DMG advises that damage can be adjusted based on the landing surface, but doesn't provide advice on how to do this. The Heroic Legendarium has some examples on how to do this.
The examples of falling damage in the UA thief-acrobat must be adjusted, since they use cumulative damage.4)
(3.5 * 6 = 21)damage, which is enough to auto-kill 3 max-HP trained men-at-arms. It is also impossible for a regular person to survive, when on earth a person can survive a fall of greater than 30'. If the DM wants to create a falling hazard, they can just create a higher cliff or a deeper pit. It's much harder to go in the opposite direction (30' rooftops will always be 6d6 damage; you can't reasonably make houses shorter, but you can make pits deeper). More info at https://deltasdnd.blogspot.com/2009/06/oed-environment.html.