A dol rune is a low tier rune that can be socketed into armor and weapons. You can cube 3 shael runes and a chipped ruby together to get a dol rune. You can also obtain a dol rune from nightmare countess. You can get a dol rune from the nightmare hellforge quest.
A dol rune requires level 31 to use.
Horadric cube recipes with dol runes
transmute 3 dol runes and a chipped emerald to create a hel rune