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Apologies if this is a duplicate (or just common knowledge) but I found it hard coming up with a way to search for this succinctly enough to get a definitive answer and I haven't really played a spellcaster before.
If I have a warlock level 5, the warlock has slots of 3rd level. If I then put my next level into a sorcerer. Can I select sorcerer spells of up to level 3, or can I only select sorcerer spells of up to level 1 (i.e. the sorcerer level). I understand how spell slots are added between classes etc, I'm just not sure of this one thing. I had a look at the multi-classing section but either didn't see it or didn't understand it when I did see it.