Originally Posted by GM4Him
BUT... I was thinking about presets for Counterspell. They could still work, but not if you implement the failed Arcana roll system. If you don't know the spell that is being cast, there is literally no way to preset Counterspell. They'd have to negate the roll altogether and allow your characters to simply know what the spell is that the enemy is casting. IMO, not a big deal. Then you'd have to make sure you have a set spell list that triggers Counterspell.
To play Devil's Advocate (I don't want presets), they could definitely work equally well with the failed Arcana roll system. Just add a single preset:
"If you fail the arcana roll, use Counterspell: Yes/No?" Perhaps you could still use information about the spell's level even in a failure? Or you use the level/CR/HP of the enemy creature...

Originally Posted by GM4Him
I am again on the fence and sliding back and forth between presets and prompts, and I still think a blending is going to be the best solution after the Counterspell fight. Larian LIKES magic and spellcasters. In Solasta, they don't typically have a bunch of spellcasters in a single fight - like maybe 1 per fight. But I'm thinking about the goblin camp fight with 30 goblins and the grove fight with 30 goblins and the duergar fight with over a dozen duergar. How many of them cast spells of some kind? It could get VERY prompt heavy. Even 1 mage and 1 cleric is likely 2 prompts per round just for Counterspell. Add Uncanny Dodge any time the rogue is hit and Shield (this happened with my paladin in a few fights - Shield reaction popups and I often said No because he's a tank already. Didn't want to waste a spell slot. So any time he was actually hit I got a prompt for Shield), and Bard reactions... yeah. It could get pretty bogged down depending on the party, the enemies you're fighting, and what reaction spells etc. that you've picked.
a.) Why do you know the Shield spell on your Paladin if "he's not going to use it because he's a tank already"? At that point, you should forget the spell and replace it with something else or (in an ideal BG3 prompt system) generally toggle off Shield prompts.

b.) "Even 1 mage and 1 cleric is likely 2 prompts per round."
- It is only 2 prompts if you always respond "no" on the first prompt and you have enough spell slots left.
- Didn't you just write multiple paragraphs about how, in Solasta, being prompted 1-2 times per round was "essential" to the fight? The same would hold true here.

c.) 30 goblins or a dozen duergar with a large fraction of them knowing spells...would be "VERY prompt heavy."
- What are the chances we actually fight dozens of enemies at level 5+ when we have significant (>2) spell slots left for casting counterspell, AND many of the enemies cast spells, AND we'd be in a situation where we'd want to use Counterspell against one specific of those dozen+ enemies instead of the first or second, AND we don't use our reaction on some other ability? If any of those are not true, the amount of prompts drastically decrease.

The ability to turn off prompts for specific abilities seems essential for a BG3 prompt-based reaction system. You can then turn off prompts in encounters where you are fairly sure you won't need that reaction: e.g., Counterspell against dozens of cantrip-using enemies, etc. This fits perfectly into the 3-way: "Prompt me" / "Auto-use" / "Off" system that I'm in favor of.