In the homebrew system I am using every check or save is a d10
plus applicable modifiers.
6
or better is a success
8
4
.+1
+1
or -1
and depend upon circumstances like gear and what’s going on in the fiction.Theo has the (standard) Fighter ability Fortitude, so he adds +1 to his save vs. fatigue. Jes just makes an unmodified d10
roll.