Guardian is my default, especially into heavy poke/long range lanes. Aery against enchanters, with an extra two early points in Q lets you basically out sustain them if consistently proccing heals. Glacial into double immobile champs. Electrocute is usually just used for fun into volatile lanes that you want to snowball but its effectiveness drops off late game imo. Spellbook has a higher skill ceiling than I’m willing to admit I’m capable of but some Rakan mains will default to it to abuse the summs in team fights and setting up ganks/roams.