diff --git a/doc/src/content/docs/en/mod/json/reference/json_flags.md b/doc/src/content/docs/en/mod/json/reference/json_flags.md
index d2a8cf6bf3aa..c67958cb559a 100644
--- a/doc/src/content/docs/en/mod/json/reference/json_flags.md
+++ b/doc/src/content/docs/en/mod/json/reference/json_flags.md
@@ -983,6 +983,7 @@ Multiple death functions can be used. Not all combinations make sense.
 - `BADVENOM` Attack may **severely** poison the player.
 - `BASHES` Bashes down doors.
 - `BILE_BLOOD` Makes monster bleed bile.
+- `BIOPROOF` Makes monster immune to Bio damage (A damage type mostly used by magic mods)
 - `BIRDFOOD` Becomes friendly / tamed with bird food.
 - `BLEED` Causes the player to bleed.
 - `BONES` May produce bones and sinews when butchered.