The Gauntlet, as many veteran players will agree, is the most horrible part of the entire game.
The Gauntlet begins at level 80, and ends somewhere around 100 depending on how horrible the gauntlet was to you. The more horrible it was, the longer the fun lasts.
Before level 80, there are brackets that each person fights in. Generally, if you are level 15, you cannot fight anyone lower than level 5, and no one higher than level 25 can attack you. This holds true up until about level 79. But once you hit level 80, anyone above level 80 can attack anyone else above level 80. This means if someone is level 168, they can attack you mercilessly and there's nothing you can do to defend yourself. No amount of armor or weapons or magic or generals can protect you from their abnormally large attack and defense stats. However, there are two strategies on how to protect yourself from experiencing what is essentially high school all over again.
Strategy 1: Run Through The Pain
This strategy is fairly simple. Before you level up to level 80, invest all your skill points into energy (or if you have a lot of friends who can summon dragons, invest in stamina). Once you hit level 80, play the game as much as possible to level up through the gauntlet as fast as possible. Once you reach around level 100, people will begin to ignore you to focus on level 80 players. Since your opponent can't see your stats, they can't know how well you can defend yourself. And once you get above level 100, they might lose the battle if you allocated your stats into attack and defense, and will fight against the easy-to-beat level 80 players.
What is great about this plan is the fact that you will spend very little time in the gauntlet. However, if anyone discovers that you have little to no points in attack and defense, they may continue to attack you after you leave the gauntlet. But... you'll be in the gauntlet for so little time, that very few (if any) will be able to discover this.
Update: The current "official" gauntlet is at level 300. This is where the battle page no longer shows level brackets meaning a level 300 can show up on a level 2000's battle list.
Level 80 is still a significant level in the fact that once you reach level 80, anyone can attack you, if they find you. A level 80 will not show up outside their bracket on the battle list but if you're found through a direct keep link or from a monster battle, etc., any level player can attack you. If you are level 79 or below, a level 80 or above cannot attack you even if they find you.
The gauntlet has moved up a few times (to the current level 300) due to the fact that players keep leveling up over time. It is possible that in the future, the gauntlet will move to a higher level.
Strategy 2: Take It Like A Man
This strategy requires patience, but is generally more safe. Instead of investing all your skill points into energy or stamina, you instead invest into your attack and defense stats. You'll be in the gauntlet for a very long time, but if you invest all your skill points (starting from level 40-50 or so) into either attack or defense (it doesn't matter which one, as long as it's either attack or defense), not many people will be able to win a fight against you. The thing is with the gauntlet, is that the people who attack others in the gauntlet are people who recently left the gauntlet. These are people generally between Levels 100 and 120, who have left the gauntlet, but can't really attack a lot of people. Instead of taking a risk of attacking someone their level, they chose to attack people who are level 80-100. But once they get above level 120, they then have a choice. They can choose to fight the level 80-100 people in the gauntlet (who have very little money from being constantly attacked) or they can attack the people that are between levels 100-120 (who don't get fought as often and therefore have money to take).
This is a very long, drawn out way to say that the only people you really need to worry about are the people who are level 100-120. If you focus on putting your skill points into attack and defense, you should be able to beat most of them, thus making the gauntlet not bad at all. Though on the downside, you will spend a lot more time at levels 50-100, and only able to do quests at the pace of a slow crawl at best. Then again, once you exit the gauntlet, you should be able to attack almost everyone else without fear, unless they have an extreme amount of levels.