In lieu of a condensed, centralized article addressing the numerous pitfalls one may encounter while engaging in tabletop gaming, I thought I'd launch a sort of 'mini-series', to better elaborate upon each individual topic. Hopefully, this detailed and compartmentalized series of posts will serve to better retain your valuable attention span and increase my blog regularity.
The first installment of this series shall draw attention to a practice commonly employed by Hosts worldwide: the implementation and use of personally-created playable characters (GMPC's). The acronym, clearly inspired by the short-hand for a typical player character (PC), refers to a fully-functional avatar under the direct control of a Host. This differs from the various conjured figures at large (NPC's) in that said creation possesses many of the average adventurer's capabilities. For all intents and purposes, they too, are as talented (if not more so), as the supposed 'stars' of the campaign. This drift from NPC to PC in terms of power and importance is the center of much controversy associated with these figures. For your consideration, I shall present the main opposing sides of this debate as concisely as I can.
Horror stories abound, the majority of those who protest the use of GMPC's have, at one point or another, suffered from the traumatic encounters often inflicted by an amateur Host and its character. Said incidents, though varying by nature, often come by way of a 'deus ex machina'; an attention-monopolizing opportunity for the Host's custom-made, super-special character to show just how much better they are than the PC's by bailing them out of a tough situation. Such interventions, when used outside of the rare last-minute twist, are not just a poor method of storytelling, but also the quickest way to alienate and aggravate one's players. To be perpetually saved and placed at the mercy of a vastly superior force controlled by a supposedly impartially benevolent force is a highly disconcerting one, as it forces them into a secondary position of importance; that is, to simply drift through the story until someone stronger shows up to ultimately save the day. Unfortunately, this abuse of Host powers is quite prolific with amateur practitioners of the game, a sad fact that serves to continually strengthen the general enmity towards GMPC's.
Some are fortunate enough to have relatively pleasant experiences with GMPC's, while others have thoroughly endured an intrusive bout of escapism, but both agree that these characters can, and often are, implemented in a constructive fashion. The key, they argue, is to design a character whose strength compensates for a critical weakness of the party. Said weakness, though I certainly can't speak for all cases, typically comes by way of direct player support, such as a healer, or negotiator. In my experience, few players are eager to play the largely pacifist role of doctor/diplomat/etc., so Hosts are often found conjuring some manner of character to mitigate these flaws. For anyone who's ever stared down the possibility of a total party kill, these individuals serve as a highly-appreciated intervention (and a potential plot device, if they become too attached to said character).
Personally, my stance on this practice is entire contextual. If dealing with a group of novice players, I'll have the foresight to rectify any glaring flaws in their team dynamic with a tasteful GMPC. If Hosting an experienced group on the other hand, I shall leave the foresight entirely up to them, as they really should 'know better' by that point. If their lack of inter-party communication should fail them when team roles are called into question, they'll be all the better for the learning experience.