It got super dicey at the Creche, Lae'zel just barely escaped with all our lives.
The exact same thing happened to me on Tactician. I went in with Astarion, Gale, Karlach and Lae'Zel. My three melee characters all got downed in maybe the first 3 turns. I ended up killing the inquisitor and all the gith, using one very squishy Gale 8'D I wanted to long rest before going inside the prism, but the second we stepped outside, Lae'Zel attacked Gale, I straight up killed her and left her in Karlach's backpack the rest of the run.
Again, I die to an overabundance of lightning, just like I did on my Gale run.
In my two playthroughs on Balanced I always ended with only 1 character alive versus Ansur. On my tactician run, I killed Raphael first, grabbed his helldusk armor and the 23 constitution necklace, and that seems to help a lot with damage taken. I also made each character drink a "Lightning Resistance" potion and that negated a lot of the electrified water and lightning damage from the ground. I ended up with 3 characters alive with almost full health. He only managed to down (not dead) Shadowheart on the final hit, and she didn't really do much TBH.
There was no more ground to stand on. I just needed ONE more turn for victory. This stings.
If I got to the end and that's how I died, I think I might cry. I finished my tactician run the other night and they don't even let you long rest/regain spell slots AT ALL before the final battle. Wish I knew that before I used up all my level 3-4-5-6 spells *hrm*. I think I lucked out on the final battle. I rolled a Nat 20 (not re-rolled, not save scummed) on the difficulty 99 roll against the netherbrain at the docks, and when I got to the final battle, it had a purple debuff called "AGAINST ALL ODDS," and it reduced the brain's health and it was supposed to be over 400 but was over 330 instead.. I ended up killing the brain in 2 turns, but on Tactician it honestly looked like there were WAY more platforms disappearing. Like on balanced it looked like maybe 4 platforms, on Tactician it honestly looked like HALF the platforms were gone after the first turn. Honestly that death hurts.