The Slot Machine Casters who have positive modifiers on their key casting ability have additional spell slots available at each level per the table Bonus Spell Slots. For a multiclass spellcaster, use the highest key ability to determine extra spell slots per the Spell Slots per Spell Level chart in Chapter 6 of the Player’s Handbook (p.165 in the 2018 edition). Bonus Spell Slots Key Mod Bonus Spell Slots 1 2 3 4 5 6 7 8 9 +1 1 — — — — — — — — +2 1 1 — — — — — — — +3 2 1 1 — — — — — — +4 2 2 1 1 — — — — — +5 2 2 2 1 1 — — — — +6 3 2 2 2 1 1 — — — +7 3 3 2 2 2 1 1 — — +8 3 3 3 2 2 2 1 1 — +9 3 3 3 3 2 2 2 1 1 +10 4 3 3 3 3 2 2 2 1 The bonus spell slots don’t work precisely the same for warlocks since they only ever have one level of spell slots