Table-Top RPGs are largely dependent upon the fighting. As DM it is your responsibility to make these fights invigorating and challenging for the players. This becomes a difficult task when you realize how boring battles can become.
Recently I have been playing once again on the player side of the DM screen. It was a new experience for many as the group I played with is working on teaching everyone in the group how to DM. This was great experience for them to understand the game better and allow for their own creative plot development, but also a great opportunity to me to learn what I could be working on while being DM. What I learned from this experience, was that battles can be exceedingly boring.
It seems that battling would be one of the best parts of Table-Top RPGs, which makes sense since majority of rule books concentrate on the fighting. But if done wrong, it can ruin a great RPG for the players. The biggest problem arises from the length of the battle. Each person must take a turn, as well as all creates and other DM controlled players in the battle. Devising a battle where there are 22 monsters being fought at the same time sounds cool, but realistically takes over 6 hours to complete and makes each turn of battle last a good half an hour.
For a DM this may not be so shabby, as the DM has 22 awesome monsters to control and pummel the players with, but for the players it is like waiting in line for a rollercoaster that lasts hardly a minute. Mattering on the group, it can be extremely difficult to keep the attention of the players when taking the monsters turns. This can results in players loosing focus, and then when it does finally get to their turn it takes longer because they are not prepared. Or worse, none of the things they try to accomplish during their turn works and they just wasted a half an hour of their lives watching you do cool things with fictional monsters.
So the problem can arise that battles can last just too long. They can also be too short. It is not satisfying when the group wipes out an entire host of enemies in only a few short turns. What is the point of a healer class if the characters do not even take damage? This is why battles must be balanced. They need to be difficult enough that everyone gets their fair share of monster pummeling but also needs to be concise so people do not lose interest.
I have three suggestions for battle stereotypes in order to fix this problem. Number one is to make one overpowered enemy for all the players to try to defeat. Number two is to make a swarm, meaning a bunch of super weak creatures that can be killed easily. You can also combine these methods to do a group with a boss situation battle. Number 3 is a group of enemies that is of equal power and of equal number as the player group. Of course these battle stereotypes, as I like to call them, can be adjusted to fit the needs of the campaign and battles.
These battle stereotypes may seem obvious, but it would surprise you how many new DMs try to trail blaze their own path and it becomes a train wreck for everyone. As long as one does not stray too far from these norms the battle should be fairly balanced to meet the needs of the player and the needs of the DM.