Some background:
-My weekly game has been goin since 2009 on Wednesdays and has had between 5 and 9 members in a single campaign. Many Dungeon Masters (DMs) will tell you this is too many. For me, it is just right.
-Our group rotates DM duties every (roughly) four months. This means three times a year, everyone picks up a different character and changes their play style a bit.
As the person running the story of a pen and paper RPG, you can tell your players are going to fall into one of a couple categories. These can vary by encounter, session and campaign as the players behind these characters become more or less invested in the story, suited to the challenge or distracted by whatever is on their phone at the time. Two main types of character are the bread and butter of any encounter or scenario:
-Characters who want to be at the head of the action making decisions and engaging with your NPCs and the world as directly as possible.
-Characters who are trying to work for the team. They are supporters and will be there to buff, solve riddles and write things down.
There is a third kind of character. This person will almost always deliver the same results from encounter to encounter. This special, magical creature is the wild card. Put this player in a magic item shop and there WILL be an incident. Put them near a lever, it’s going to get flipped. Glue down all the fragile things in a room and they will find the only part not glued down and mess with it. These characters are going to make things fun every time and while your carefully laid plans will fall apart, you will be better off for it.
This brings me to my specific example. A few weeks ago, a major civic official gave my players a bank vault to hide some dangerous artefacts in. To cover their bases, they put a false chest in that vault then opened their own separate bank account and put the actual valuables in there instead. This would have been a fine plan by itself. The Wild Card offered a great idea of adding a supremely dangerous trap to enhance the plan.
The suggestion was to put the valuables inside of a portable hole (a flat carpet-like item linked to an interdimensional space) which was then put inside a bag of holding (a large drawstring pouch with an interdimensional space inside). It is well known that putting the one into the other will break reality. By doing this in the safety of an anti-magic field, they did not have any such issue at the time but they left the items inside that anti-magic field just waiting for some unknowing robber to come for their stuff.
While our characters gallivanted around the city disintegrating things, fighting necromancers and shopping, this little beauty was just sitting there in a vault. Now, perhaps you have already concluded that a box full of stuff the bad guys of the story want which also contains a reality destroying bomb is going to be stolen. Perhaps you have also concluded that as a DM I would be mad not to allow this to have the worst possible effect. You would be correct on both counts.
After fighting to keep these dangerous artefacts out of the hands of the fiends (literally) who seek to use them to bring about a terrible plot, our heroes sat in a tea shop interviewing a sage while their reality bomb was detonated on the far side of the city. The effects tore the city apart turning blocks of houses, shops and civic buildings into floating islands of reality in a sea of red swirling chaos.