In essence, leveling in Diablo 3 takes two separate paths.
The first time I realized I could just give players a level whenever I felt it was appropriate for the story, I almost fell over.
During an inverview with content creator MrGM, Lead Game Designer for World of Warcraft Morgan Day revealed that, with the release of the next expansion, Shadowlands, heirlooms will no longer provide an XP bonus.
Two of my favorite games -- Diablo 3 and World of Warcraft -- both have leveling up and gaining XP as core parts of their gameplay.
Blizzard pushed an update to the Battle for Azeroth beta servers that's increased the amount of XP required for leveling, and the amount of AP needed for the Heart of Azeroth at later levels.
Blizzard's Heroes of the Storm Core Concepts guide continues with part two of its Team Leveling overview.