Let's start with the basics of spell slot mechanics for casters, which work quite differently than you might expect. Prepared casters can swap their spells whenever they want outside combat, and any class can use spell scrolls which opens up some interesting options. The standard rules about bonus action spells are gone so you can actually cast two big spells in one turn if you have the slots for it, something you definitely want to remember for tough fights.

When it comes to specific classes, Warlocks still get their slots back on short rests but can learn 6th-level spells at level 11 making them more flexible. Ritual casting is streamlined where Rangers and Warlocks can summon familiars without using slots though Wizards still need to spend them. Speaking of Wizards, they've got some nice perks where they can learn any scroll matching their slot level and all casters can use their slots more freely than normal making magic feel more dynamic and spontaneous.