"If you would rule the world quietly, you must keep it amused."
–Ralph Waldo Emerson
While not an avid Descent player, Mr. Emerson presents an intriguing thought to those aspiring to greatness as Overlords. Keep the players entertained while handing them their heads. Of course, in order to do this, an Overlord must first know the secrets to winning. While some of the following seem malicious, it is an experienced Overlord that can execute the following without alienating the players.
Always kill when able. While most Overlords aspire to malevolence, there is always the occasional wishy-washy one that is empathetic to the plight of the heroes. If you find yourself sparing the lives of heroes thinking they will have a better game, resist! There is no outcome that will please both the heroes and the Overlord equally since both wish the destruction of the others' forces. Because of this, it is often better to demolish the heroes quickly and suggest a replay of the scenario. That way, if the heroes learn a little something, they can make a better showing. And if they happen to learn a lot… you already have a one game lead!
Always pick on the weak (even if you must kill your own creatures). While the Overlord gets to control a myriad of creatures, the reality is that the Overlord is David more often than Goliath. At least one or two of the heroes will constantly be trying to goad you into an attack which will result in obliterating your monsters while doing minimal damage to the heroes. However, one hero in the party is always easier to kill than the rest. This is usually the ranged assassin that annoys you with guerilla style bow attacks who skulks toward the rear of your group. Always attack this person! Even if this hero is only worth a paltry 2 conquest points, it is usually easier to kill this character multiple times than to take on the heavily armored fighters.
Remember two things when using this philosophy of battle. First, the weakest player can change during the middle of the game. A weakling with a devastating weapon can cause problems while a hero that only obtained a weapon he cannot use can become a much more appealing target and your new best friend. Second, if the attack that can kill a hero will kill your monsters, take it anyway. Your monsters will usually die in one strong hit anyway, and if that hit is one that also kills a hero then thank them for their loyal service and let loose your fury!
Always be a trusted mentor (when it suits you). It is often a fact of life that the player taking up the Overlord's mantle is the most experienced player at the table. As such, newer players always look to the "team" for good options. As the Overlord, you should always be part of that team. At the beginning, the excuse is that you are helping them get the feel for the game. At this point, legitimate advice is always the best medicine and it will help streamline things later on. There will be a point toward the middle of the game however when a choice must be made to concur with the assessment of one of the players (which would indeed be an excellent play) or offer up the "possibility" of an alternative which also has merits. As you talk them through it, they realize you have their welfare at heart and take your advice since they are tired of the "know-it-all" wizard virtually playing for them anyway. It won't be until several turns later that move you had been planning the whole time comes to fruition. You blame this on luck. Finally, with virtually no conquest points they frantically search for a way to at least face the final boss. You will remain silent. This is the way of the Malicious Mentor.
Always point out what the heroes should have done to avoid Armageddon (only after it is too late). Heroes often make a mistake that is partially due to the fact that the Overlord is in control of most of the hidden information. Rash moves from impatient players can also open up vulnerabilities the Overlord should exploit. It is often useful to point out what the heroes did wrong in the situation, especially if there were multiple ways that the party could have avoided the calamity. The Overlord does this so that the heroes can trust his tactics when using the previous technique as well as encouraging the players to play more conservatively. They are more apt to move slowly when they see they are making mistakes. Plus, the slightly demoralized hero can be putty in your hands.
Always question the wisdom of a heroes' move (especially ones leading to forward progress). A good group of heroes will move forward as quickly as possible. This is readily apparent to veterans that understand that the treasure dynamic is backwards from normal games of this type. In order for heroes to defeat monsters in Descent, they must get treasure. This goes against the thinking that heroes are slaying monsters to receive treasure. As such, a lone veteran may break apart from the group to surge ahead and gain treasure at risk to himself. At this point, less experienced players will start to rebuke him, siding with a more conservative approach that risks less. This is a perfect time to institute the "Questioning of Judgement." This technique is employed by feigning to show mercy by showing how bad a move is since you will have good spawn points, how you can cut this player off from the group, and/or how he is leaving the group's flank or some other tactical nonsense unguarded. Your true mission in this case is not to convince this player of the fallacy of his move, but rather his team. It is rare that a player will go against his team if they are all convinced that the move is horrible. When he wants to go back and do his move over, say that it is no problem and you will go ahead and let him. The heroes will now be playing more conservative but this also impedes their progress. Be aware though, that if you fail to convince the choir that this soloist's move is a bad idea or the aggressive playmaker ignores his team and moves anyway, a vicious reprisal is called for. You must kill him, or even better, one of the hero's party that is lagging behind. Be reckless and throw it all down. Then blame the hero and his forward aggression. Be sure to say that he should have heeded your warnings and state that you will not be so forthcoming with the advice next time.
Always stall out the heroes. As the Overlord, time is always on your side. The more the heroes spend trying to become fully safe, the more time you have to draw the cards you need to pick off on of their number. This technique can win you the game since the heroes will lose conquest once the Overlord deck runs out. Do not advertise this though. Instead, keep the attention of the heroes elsewhere. There are two good distraction possibilities. First, make the heroes paranoid. Point out open lines of sight behind the heroes, even if you don't plan on using them. Talk aloud about how there are too many trap cards in the deck. This is always effective right as heroes begin to consider whether or not to open a treasure chest. Paranoia will often cause heroes to clear a room, spread thin in order to cover lines of sight, and cause heroes to move more slowly in general since they believe the unknown is worse than the opposition already revealed on the table. Second, the Overlord can utilize a "net" defense. The object here is to use guerilla style assaults in conjunction with an aggressive defense to force players to move to attack your minions while spawning a great deal of monsters. Try to attack with monsters and then retreat away so that heroes cannot stay in place and battle as much. Put your fodder as the first line of defense so that stronger monsters behind get to counter attack. This kind of wave defense and counter attack is also a good way to keep players suspicious since monsters always attack, right? A foreboding front line will also give players the idea that all heroes should be near the line to fight or support. Of course, this is when a backdoor spawn is most useful.
Always be an attentive rules lawyer. Interestingly enough, it is to your advantage as the Overlord to follow the letter of the law. The rules help you to survive and give you the edge in several situations. The first rule which you should always enforce is the declaration of which action a hero will perform. If a hero starts his movement, immediately ask which action he is taking. After he has proceeded through the first part of his turn, do not allow him to change which action was declared. This sets a precedence and will force players to think about things a little more carefully. If they don't and players just call out actions off the cuff, it will add to the body count sooner or later. The second rule to enforce is the fact that there is no trading items, there is only the giving of items. It is also pertinent to remind players that this costs one movement point. This rule will sometimes delay heroes from gaining a good piece of equipment since the person needing to give them that equipment has already gone. This gives you a window to attack and hopefully kill this person before he acquires a more powerful weapon. Finally, heroes should not be allowed to replay their turn if another player has started their turn and the previous player has flipped over his turn marker to the "X" side. The player that does this is usually the "thinker." This player probably wanted to map out all possibilities before moving. After moving, the thinker sees a slight imperfection in his move. Do not give in to this! Instead, kill a hero exploiting this weakness (or perceived weakness). This will cause heroes to slow down and second guess themselves.
While these Descent Decrees are only some of the basic techniques the Overlord should employ, it is by no means exhaustive. If you think that some of the Decrees are hard on the players, then you are perhaps called to be a hero instead of an Overlord.
For those true Overlords out there, I urge you to remember the words of Profion in regards to the heroes, "Let their blood rain from the sky!"