What is your preferred alternative to spell slots?

Most levels that see an increase in spell slots give you about levels of spells per level Levels 1, 3, 5, and 9 give you more Levels 12,

spell slots you gain from the Spellcasting class feature to cast warlock spells you know Multiclass Spellcaster: Spell Slots per Spell Level Level, 1st, 2nd

spellcast slot Spell Slots You determine your available spell slots by adding together all your levels in the bard, cleric, druid, sorcerer, and wizard

spell slot counter To cast one of your warlock spells of 1st level or higher, you must expend a spell slot You regain all expended Pact Magic spell slots when you finish a short