Spontaneous casting refers to casting spells from a spellbook without previously allocating a spell slot to the spell. A spell slot of the same level as the spell — after considering metamagic — is still consumed by such a casting. Sorcerers and bards can cast any spell in this manner, and as a consequence these classes never allocate spell slots to specific spells. Clerics can spontaneously cast the "cure" and "inflict" spells (from minor to critical wounds), which will consume a readied spell slot not assigned a domain spell (the leftmost such slot of the appropriate level, when viewing the spellbook).