Baldur's Gate 3 transplants the rules of Dungeons & Dragons into a video game, but one important rule involving spells has been ignored, making spellcasters stronger than they are in the tabletop game.
There have been many D&D video games over the years, and some have attempted to directly use the rules from the tabletop games. Neverwinter Nights featured an almost perfect conversion of the third edition rules of D&D, while the first two Baldur's Gate games had the task of using the janky Advanced Dungeons & Dragons rules. The video game format is perfect for adapting the combat rules of D&D, but there are still limits to what can be accomplished in a virtual environment.
Baldur's Gate 3 uses the rules for the fifth (and current) edition of D&D, with some changes. The combat was altered to be more like Divinity: Original Sin 2 (a game made by the same developer), with grids being replaced by measurements on a 3D battlefield. Some of the D&D character classes and spells were altered in Baldur's Gate 3, but a major change to the spellcasting rules has made Clerics, Rangers, Warlocks, and Wizards more effective than they are in the tabletop game.
D&D's 5e Bonus Action + Cantrip Spell Rule
The majority of the spells in D&D have a casting time of one action. There are some spells that have a casting time of Bonus Action, which means that the player can also take another action during the turn the spell is used. It's explained on page 202 of the Player's Handbook that casting a Bonus Action spell means that if the player wants to cast an additional spell, then it has to be a cantrip. This is one of the most easily missed rules in the Player's Handbook, which is why it's highlighted at the start of Tasha's Cauldron of Everything. A player who casts a Bonus Action spell (like healing word) can still attack with their weapon or use an item during their turn, but they can only cast a cantrip-level spell if they want to use more magic in the same round.
What Baldur's Gate 3 Changed About Spellcasting
Baldur's Gate 3 has scrapped the Bonus Action rule for spells. In Baldur's Gate 3, all spellcasters can use a Bonus Action spell and a spell of any other level during their round in combat. This means that spellcasters are a lot more effective in combat than they would be in a real game of D&D, especially Clerics, as they can cast cure wounds and healing word in the same round.
It's unclear why this change was made, but it was likely to make spellcasters more interesting to play in combat. D&D rules care more about balancing combat, while Baldur's Gate 3 is focused on making battles as fun and as exciting as possible. The brutal difficulty of the game, coupled with the enemy A.I. often focusing on party spellcasters means that the rule could have been abandoned to give the player more of a chance during fights. Baldur's Gate 3 is still in Early Access, so it's possible that the developers will add the rule in later, once more of the bugs have been ironed out and the difficulty has been balanced. The removal of the Bonus Action spell rule is a positive thing, in our opinion. It can be frustrating to see players become too strong in D&D, but video games have more of a focus on power gaming and smart combat strategy than tabletop RPGs, so making the spellcasters more useful was a smart move.
Baldur's Gate 3 is currently in Early Access and is available for Google Stadia and PC.