Back when D&D had prestige classes, Mystic Theurge was one of my favorites. This prestige class was made by multiclassing an arcane and a divine class. The class uniquely handled magic, however. Theurge’s sacrificed high-level spells in exchange for increased lower level spells. This change in spellcasting was mighty with the versatility you got from gaining more lower-level spells. That is why many players considered this prestige class the ultimate caster. This got me wondering, can we get the same effect in 5E? Obviously, multiclassing is very different in 3.5 compared to 5e. Still, I feel we can get a very similar result and can create the ultimate caster in 5e.
Multiclassing From Past To Future
When you multiclass in 3.5, very few things combined between classes. For example, if you took a level in the wizard and a level in bard, you treated all abilities and spells separately. This means that you had your bard spells and wizard spells, and you prepare them and cast them individually. This was great since you do not combine spell slots you get many lower-level spells to cast.
In 5e, however, multiclassing spellcasters combine their spell slots so you can never get more spell slots. This was done, so any multiclass will get the same number of spells per day as a full caster class. While this does not get you a plethora of lower-level spells to cast, it does give you access to higher-level spells. Also, just like with 3.5, you prepare spells separately, but we will get to that later.