I had never really appreciated the concept of Counterspell until now. Characters that are in range to see the actual spellcasting get to roll an arcana check to identify the spell, and then if any one of those characters have Counterspell, they get the option to counter it. If you fail the arcana check but are still in range to interrupt, you can still counter it, but you won't know what spell you're trying to halt.
There's a lot of strategic layers to unpack here.
Also, I had been previously concerned that Solasta was actually pretty easy before. This patch made some fights brutally hard, but still feeling very fair within DnD rules. Almost feels like I'm playing a X-COM game at times, really - and those games are considered the pinnacle of tactical turn-based combat for a reason.
Yeah, and there are reasons for and against countering the harmful spells. Since Counterspell is a level 3 spell, and you need to have the spell memorised and have the spell slots to cast it, you'll have to consider the potential harm should the party members fail their saving throws vs burning a spell slot to counter it. This is an example of the tactical considerations players get to make, which is sorely missing in BG3.