Planned Entrances have a spectacular history of failure in table top RPGs. Whether it is a Key NPC that is to be introduced, the BBEG supposed to be showing up for some early heckling and hazing, or just a plot giver that needs to make a deal with the PCs, the internet is full of stories of these interactions going bad. The most famous is the BBEG intro where the GM has wonderful plans about how the evil villain is going to show up, ruin the PCs' day, and then vanish in a cloud of smoke. Only, upon execution, the BBEG shows up, gets dimensionally anchored, and a critical hit sneak attack/smite one shots him before he can do anything. Today I want to talk about these intros, and how to plan them for - hopefully - better success.
Who Is the NPC?
The first question to ask is just who is your NPC? I don't care about their name for this, but more their role. Is this supposed to be the Big Bad Evil Guy? Is it supposed to be an ally that is hiding in the shadows? Perhaps someone you want the PCs to have a complex "are they friends or enemies" relationship with?
While asking yourself this, also ask if you have to introduce the NPC in the way you're thinking. Obviously you don't have to do anything, but just make sure that you're not trying to force a particular interaction because you think it will be cool, even though it is likely to get the wrong reaction from the players.
Who Are Your PCs?
Speaking of, who are your PCs? Are they the type to shoot/kill first and ask questions later? Do they over-react to people lying or being shady around them? Does it take them a bit to realize the difference between a social encounter and a combat encounter after having a few combat encounters that day? These are all fairly common in RPG groups and worth noting if your PCs do them. Having an "ally" run at the PCs with a sword up over his head after the PCs just had a life or death fight is likely going to end with a dead ally.
What Could Go Wrong?
It seems backwards, but you really should approach planning these intros starting with what could go wrong. For example, if you're running a modern day super spy game, and the BBEG is going to make a grand entrance on a helicopter...what do you do if a PC shoots down the helicopter? What do you do if a PC shoots the BBEG? What happens when the demolitionist procs their hero point ability to plant charges all over an area and detonates on said BBEG?
The goal here isn't to make it so that the PCs can't do anything - if you want to do that, just tell your players they're going into a cutscene and leave it at that - but rather to make it so that you have some protection against the PCs derailing the game on accident. Even still, be prepared for the train to go off the tracks and hard, but you can have contingencies for most cases.
How Can Your PCs Still Be Awesome During This?
Obviously the idea behind a grand entrance for an NPC is to make the PCs realize how awesome/badass/important this character is. But how can the PCs also be awesome during this? One of the reasons a lot of introductions end in tragedy (for the GMs plans) is because the PCs are in the game and still trying to get their moments or keep themselves safe. So how can you work with that to let the PC feel awesome, but still sell your moment?
Side Note; Imperial Valor
One thing I love in Fantasy Flight Game's Edge of the Empire system is a trait called 'Imperial Valor.' Imperial Valor is a trait that only NPCs can have (specifically Imperial Officers) and what it does is state that if someone with Imperial Valor is targetted with an attack, they can make a near by Imperial character that is not them take the attack instead. This works beautifully for protecting a BBEG on introduction, selling the importance, and still letting the player feel awesome. How so? BBEG arrives and starts his thing. The PC goes to take his shot and succeeds. A bodyguard jumps in the way saving the guy, but the shot is still impressive and perhaps leaves a meaningful car. The villain singles out said hero. There is a connection made. Drama and amazing gameplay/storytelling can now ensue.
the point of all this is simple. Don't plan your scene to happen in a vacuum. Take the time to try and predict what your PCs will do, or what they could do, and how you can use that to help make the moment feel more real.