Let's say the party arrives in the jungle and stumbles upon an Amazons civilization. In addition, imho it's an interesting feat to build homebrew around. For instance, a Cleric with Find Familiar can deliver Cure Wounds at range. Otherwise, Magic Initiate can still be a fun addition regardless of main class and MI class correspondance. When you absolutely want a certain spell on top of your dip, but don't want to take another level in said class (and/or can't afford to) When you want to go for some sort of perfectionnist/lore seeker character concept Arcane Trickster with Find Familiar dips Wizard - can add the spell to their spellbook When your 'martial' character who wanted to dabble in magic without multiclassing ends up multiclassing. You can only cast it with slots if both are X.

Some might start arguing that if an X class spell happens to be on Y list, Y should be able to cast Magic Initiate: X's spell with slots, but RAW that's incorrect.

Bard taking MI:Bard? spell is perma-known, can be cast with slots. The tl dr is that MI must be of the character's class and a character has to follow their 'normal spellcasting rules'. Saw a chap discussing the X Initiate spells in the New Players Questions section, and it reminded me of Sage advice stating that it's sometimes possible to cast Magic Initiate spells with slots, not just use an MI spell for free, once per long rest, at the lowest level.

Magic initiate 5e