companions? CC Zealots and use counter when you think your going to needed it. Line of sight, use companion as meat shield, what's your inventory, potions?, cleric?, grease bottle? Barrels around? where are we? How many turns till he usually casts death?
There is usually a good amount of choices you can do in any given scenario
Counterspell isn't in the game yet from what I can gather its a 5th level spell (3rd level spell slot). I know there is a couple reaction spells for warlock already in the game, do you guys cry yourself to sleep when something doesn't work like you wanted it to? Use another tactic or maybe save scum.
I asked you a very simple question. I defined the example. The turn order is set; everybody mentioned in the initiative is mentioned. That is the scenario. There is no save-scumming for a better situation; this is the encounter I'm defining. It's turn one. That is the turn order as rolled; the lich is going to cast finger of death on you. The zealots are going to cast minor buff spells or cantrips. That is the entirety of the scenario; a door has just slammed shut behind you, leaving you in a blank, empty, round room that is 30 feet across.
Your goal is to counterspell the finger of death, because not doing so will result in your death from the base damage alone, even if you make the save. How do you do it?
Any sane implementation of the rules allows you to do this, straight up, without fussing; it's a tactical decision that you as a player can make - to not use your reactions on things that you don't want to use them on, and to use them on things that you do. It's your choice.
You could certianly try to crowd control the zealots, as you mentioned. You try that - it only sticks to one of them. Now what? You just die and reload, and hope it sticks to both of them next time? Why do you feel that that is better than being able to choose when and when not to use your own spells?
Your made up scenario is based on one character which doesn't involve bg3, its a bad test/scenario and your tunneling the outcome in your favor.
This doesn't prove anything. Sorry btw I didn't make my answer simple enough for you.