Final Map Boss in each Map has +(1.8-2.4)% chance to drop an Elder Guardian Map (Tier 14+)

What this record tells you

This is a prefix modifier available from level 78. Its listed spawn tags determine which item families can naturally receive it.

Positive spawn weight means the modifier is eligible for that tagged item family. A zero weight blocks it for that tag. Weight is relative—not a simple percentage by itself.