All spells needing to calculate a hit chance is annoying, the chance to hit should be separate to a saving throw as it was in previous D&D games, but I guess this is one of the 5e changes.
In 5E there are two different ways a spell can connect. Spells that can be resisted or dodged (AOE) work based off a save v. a relevant stat. If the spell needs to be aimed, then it is a spell attack roll using the caster’s Dex.
In BG3, they always just show a percentage of success, but sometimes that percentage means the chance the enemy will blow their saving throw.
