The character tiers are the three stages a player character goes through in 4th edition Dungeons & Dragons. The thirty levels of a player character's career are divided into three tiers: the heroic tier (1st level through 10th level), the paragon tier (11th level through 20th level), and the epic tier (21st level through 30th level).
When you leave one tier and cross the threshold into a new one, you experience some major increases in power. Many feats are tied to a specific tier (for example, you must be in paragon tier or higher to take feats like Polearm Gamble). Other effects (like the damage from Weapon Focus) increase with your character tier. At the same time, the threats you face in a higher tier are much more lethal.
In the heroic tier, your character is already a hero, set apart from the common people by your natural talents, learned skills, and some hint of a greater destiny that lies before you. Your capabilities are largely determined by your choice of character class and to a lesser extent by your race. You move around on foot or on a relatively mundane mount such as a horse. In combat, you might make mighty leaps or incredible climbs, but you’re still basically earthbound. The fate of a village might hang on the success or failure of your adventures, to say nothing of the risk to your own life. You navigate dangerous terrain and explore haunted crypts, where you can expect to fight sneaky goblins, savage orcs, ferocious wolves, giant spiders, evil cultists, and bloodthirsty ghouls. If you face a dragon, it is a young one still searching for a lair, one that has not yet found its place in the world. One, in other words, that is much like you.
In the paragon tier, your character is a shining example of heroism, set well apart from the masses. Your class still largely determines your capabilities. In addition, you gain extra abilities in your specialty: your paragon path. When you reach 11th level, you choose a path of specialization, a course that defines who you are within a certain narrow range of criteria. You are able to travel more quickly from place to place, perhaps on a hippogriff mount or using a spell to grant your party flight. In combat, you might fly or even teleport short distances. Death becomes a surmountable obstacle, and the fate of a nation or even the world might hang in the balance as you undertake momentous quests. You navigate uncharted regions and explore long-forgotten dungeons, where you can expect to fight sneaky drow, savage giants, ferocious hydras, fearless golems, rampaging barbarian hordes, bloodthirsty vampires, and crafty mind flayers. When you face a dragon, it is a powerful adult who has established a lair and found its place in the world. Again, much like you.
In the epic tier, your character’s capabilities are truly superheroic. Your class still determines most of your abilities, but your most dramatic powers come from your choice of epic destiny, which you select at 21st level. You travel across nations in the blink of an eye, and your whole party might take to the air in combat. The success or failure of your adventures has far-reaching consequences, possibly determining the fate of millions in this world and even planes beyond. You navigate otherworldly realms and explore never before seen caverns of wonder, where you can expect to battle savage pit fiends, the ferocious tarrasque, sinister sorrowsworn deathlords, bloodthirsty lich archmages, and even demon princes. The dragons you encounter are ancient wyrms of truly earthshaking power, whose sleep troubles kingdoms and whose waking threatens the world.