Diablo 4 Season 12's short duration makes fast leveling from 1 to 60 more important than ever, and the new Killstreak system helps by giving extra XP and seasonal reputation for chaining kills. The general approach for all classes is straightforward: start with seasonal quests, move on to Helltides, and weave in Capstone Dungeons, elixirs, incenses, and group play to stack XP multipliers up to...