Tiers of Play
With each new level, characters acquire new capabilities that equip them to handle greater challenges. As characters advance in level, the tone of the game also changes, and the stakes of the campaign get higher. It's helpful to think of a character's (and a campaign's) arc in terms of four tiers of play, describing the journey from a level 1 character just beginning an adventuring career to the epic heights of level 20. These tiers don't have any rules associated with them; they point to the fact that the play experience evolves as characters gain levels.
Tier 1 (Levels 1-4)
In tier 1, characters are apprentice adventurers, though they are already set apart from the broader populace by virtue of their extraordinary abilities. They learn their starting class features and choose a subclass. The threats they face usually pose a danger to local farmsteads or villages.
Tier 2 (Levels 5-10)
In tier 2, characters are full-fledged adventurers. Spellcasters gain iconic spells such as Fireball, Lightning Bolt, and Raise Dead. Most weapon-focused classes gain the ability to make multiple attacks in a round. The characters now face dangers that threaten cities and kingdoms.
Tier 3 (Levels 11-16)
In tier 3, characters have reached a level of power that makes them special among adventurers. At level 11, many spellcasters learn reality-altering spells. Other characters gain features that allow them to make more attacks or to do more impressive things with those attacks. These adventurers often confront threats to whole regions.
Tier 4 (Levels 17-20)
At tier 4, characters achieve the pinnacle of their class features, becoming heroic archetypes. The fate of the world or even the order of the multiverse might hang in the balance during their adventures.