. If you kill Icara, she will never spawn when you find Zandalor's body at the end of the Source Temple, effectively preventing any further progress.
. This gamebreaking bug was reported several times on Steam as early as 2016 and Larian employees acknowledged it and the fact it wasn't normal behaviour.
Sources:
https://steamcommunity.com/app/373420/discussions/0/490124466471382706/ https://steamcommunity.com/app/373420/discussions/0/2132869574258305580/ https://steamcommunity.com/app/373420/discussions/0/1326718197206479771/ https://steamcommunity.com/app/373420/discussions/0/1693843461184866458/ https://imgur.com/a/Bgop7he. The only known "fix" is to use an EE Pyramid exploit used for speedruns and described
here.
. Drop pyramid on the ground, start dragging with LMB and press RMB. Let go of RMB and use directional keys to move to desired coordinates on the map. Drop the Pyramid and use the other one to teleport to it.
. Coordinates to the last boss are: 892:150 but you can do 908:84 if you wanna start a tad bit earlier. This still makes you skip most of the end fights and story though.
