According to
https://diablo2.diablowiki.net/The_Countessshe has 108fire res and 130 cold.
So she is immune to both but fire res can be broken by infi/conv/lr, cold can be broken by infi/conv + lr (if its -155 res in sum)
This post was edited by Hell_of_Dammed on Jan 3 2021 01:55pm