Models with this special rule are Steadfast in the first round of close combat. If they have the Stubborn special rule, they instead become Unbreakable in the first round of close combat
BackSource: Warhammer Armies Project: Unofficial 9th Edition (v2.2)
Models with this special rule are Steadfast in the first round of close combat. If they have the Stubborn special rule, they instead become Unbreakable in the first round of close combat