Larian seems to be intent on using an automatic system for triggering reactions, with the goal of keeping the combat fast-paced - especially in multiplayer. It's not a terrible goal to keep the combat flowing smoothly, but I remain unconvinced that it is the best idea. The essence of the concept is essentially saying:
“Players don’t actually want to choose when to spend their reaction resource in this game based around resource management and tactical thinking, they want an algorithm to do it for them.”
D&D 5e is a game where careful managing of resources, and tactical combat are important. Letting an algorithm decide when to use reactions is going to lead to trouble, because context is important, and an algorithm is likely not going to be granular enough to understand that - especially in a game as deep and as complicated as D&D. It does not help that the UI currently is missing an indicator for the AC of characters, which is vital to know for these features.
The Shield Spell and the Bard's Cutting Words feature are good examples of likely troublesome situations even though neither are implemented in the game yet. The Wizard's Shield spell is an 1st-level Abjuration Spell and a Reaction Spell. It consumes a spell slot to temporarily increases the Wizard's AC by 5 until the start of their next turn. As such, it is useless if an enemy attack would already miss, or if the enemy attack exceeds the Wizard's base AC by 5 or more. Now, potentially, those conditions could be added to an automatic trigger, so it can only trigger in the sweet spot. But it shares the same problem common to all automatic reactions - choosing when to trigger it or not. If the Wizard is next to an enemy caster and moves away, they're not likely to want to spend a spell slot to avoid damage from an enemy caster's weak melee attack.
The Bard's
Cutting Words is even more of a problem.
Also at 3rd Level, you learn how to use your wit to distract, confuse, and otherwise sap the confidence and competence of others. When a creature that you can see within 60 feet of you makes an Attack roll, an ability check, or a damage roll, you can use your Reaction to expend one of your uses of Bardic Inspiration, rolling a Bardic Inspiration die and subtracting the number rolled from the creature’s roll. You can choose to use this feature after the creature makes its roll, but before the GM determines whether the Attack roll or ability check succeeds or fails, or before the creature deals its damage. The creature is immune if it can’t hear you or if it’s immune to being Charmed.
It is commonly used to try and make an attack which would hit turn into a miss instead. The part where a human player in a tabletop game would intervene is after the attack roll, but before the human DM rolls damage dice. Right now, the game rolls for a hit and then automatically deals damage, because it can do lots of calculations at once. Is an automatic algorithm going to be able to accurately determine when to properly use this? Not a chance.
It's likely that to preserve the automatic reaction system, Larian will merely cut out the Cutting Words feature from the Bard, giving players even less of a reason to play as one than the 4-person party size limit already does, which is not a great place to be for a "Jack-of-All-Trades" class to be in a game which already has 4 key roles which need to be filled.
Feather Fall is another instance. It's no longer a reaction, but a bonus action, which makes it completely useless for its intended purpose of reacting to an action which happens on another character's turn.
There are no doubt other instances where automatic reactions are problematic as well. I understand that in a multiplayer game, keeping it fast-paced is a good idea, but at what cost will the increased speed come?
Right now, reactions can be enabled or disabled, and ordered in order of priority. (I think. I know I moved Lal'zel's "Riposte" to before her "AoO" reaction and that worked.) The best idea I have is a combination of that same priority list of enabled reactions, and a forced slowdown where if a reaction condition is met, the game slows down and the player has 6-10 seconds to decide whether to use the reaction or not, with the default being on. It's probably not perfect, but it does give the player more control, and control over when you spend resources in a game where that is vital to success is a good thing.
