So, I forget sometimes what spells are in PHB and which aren't. So, fine. Temporal Shunt and Silvery Barbs aren't in PHB and likely not in the game.
That's not the way the presets would work based on what I was suggesting with presets. Presets would be set up prior to combat. You'd access the Reactions screens and set up the conditions that would trigger the Reaction. You can tweak them during your character's turn, but for the most part they are set up by you NOT during combat. That's the whole point of presets.
So, for example, Uncanny Dodge would be activated outside of combat as a reaction you want your rogue to do. Let's say you want to set Uncanny Dodge to only trigger if an enemy does 15 damage to you. You set the value to 15. After all, why would you want to waste your reaction on an enemy who only does like 4 damage to you. You'd waste Uncanny Dodge by cutting 4 in half to 2.
For Counterspell, you set up the conditions outside of combat and activate it IF you want to use it in an upcoming battle. Or, like Passive Mode, you leave it active all the time because you always want to use it if you've prepared it. There would be a default list of spells that you would want to always counter that would trigger the reaction, and you could tweak the list to your specifications.
It would look something like this in the game:
Lae'zel, Astarion and Gale at Level 6 facing Nere and the duergar. Lots of potential spellcasters in the room. You had Counterspell activated on Gale because you like it. You also always have Astarion's Uncanny Dodge.
Round 1. Nere goes and casts Misty Step. He then casts Lightning Bolt. Counterspell automatically triggers - not on Misty Step because it's not on your preset Counterspell spell list - but on Lightning Bolt because it IS on the preset spell list. No prompts or nothing. The spell simply triggers and stops Nere from casting Lightning Bolt.
Nere was not expecting this and he tries to flee. He is in close range to Lae'zel, so he triggers AOO. No prompt. Lae'zel simply uses her Reaction to attack Nere. Why? Her preset for AOO is set to All Enemies, meaning any enemy who enters melee with her and tries to flee will trigger AOO.
But wait! You also set Lae'zel to use her Battlemaster Maneuver Menacing Attack coupled with her AOO. So, she not only hits Nere, she uses her Menacing Attack too.
Duergar's turn. She runs up to Astarion and hits him, dealing 14 damage. No Uncanny Dodge triggered. Thrinn goes next and runs up to Astarion, attacking him and dealing 25 damage. Uncanny Dodge is triggered because the preset was set to 15. So, Astarion automatically uses his Reaction and cuts the damage in half to 12.
And how long did it take me to set this up beforehand? I pulled up the Reaction screen for Astarion, activated Uncanny Dodge, set it to Damage > 15 and clicked Done. Then I went to Lae'zel. AOO is already set by default to All Enemies, so I just activated my Menacing Attack AOO and set it to Enemies with Current HP > 15 so that she'd only use it on enemies with more than 15 HP. Don't want to waste a Superiority Die on enemies with barely any HP.
Finally, Gale's Counterspell. Yeah, this would take a bit longer. I'd pull up his reactions and turn off AOO because I wouldn't want to waste his reaction on AOO. I then check the default list of spells for Counterspell and I uncheck those spells I don't want to trigger it, ensuring that only those spells I do want to trigger it are checked. Edit: keep in mind though that there is already a default list. You're just tweaking it. Maybe the list has Darkness on it and you think that would be a waste of a level 3 spell slot to counter it. You click and uncheck it. Done. It's only a little work if you don't like the default list.
So, it's a bit of work on Counterspell in advance, but it saves from stopping every time someone casts a spell.
Imagine if the above combat scenario happened where Nere wasn't first. It could very literally happen like this:
Duergar casts Shield of Faith. Prompt. Counterspell? You click No. Another duergar casts Enlarge. Prompt. Counterspell? No. A duergar hits Astarion and does 4 damage. Prompt. Uncanny Dodge? You click no. Thrinn hits Astarion. She does 25 damage. Prompt. Uncanny Dodge? Yes. Duergar casts Enlarge. Prompt. Counterspell? No. Mindmaster casts domination spell. Prompt. Counterspell? Ponder a bit. Should you? It's a pretty serious spell. You finally decide. You're saving it for Nere. No. Nere casts Misty Step. Prompt. Counterspell? No. Nere casts Lightning Bolt. Prompt. Counterspell? Yes. Nere triggers Lae'zel's AOO. Prompt. Use AOO with Maneuver? Pick Maneuver.
