As the High Matriarch of the Sisters of Sigmar's Mercy, Bertha must join a unit of Sisters of Sigmar if possible. In addition, the unit becomes Stubborn while she remains with it.
Source: Warhammer Armies Project: Unofficial 9th Edition
As the High Matriarch of the Sisters of Sigmar's Mercy, Bertha must join a unit of Sisters of Sigmar if possible. In addition, the unit becomes Stubborn while she remains with it.