A shael rune is a low tier rune that can be socketed into armor and weapons. You can cube 3 sol runes and a chipped sapphire together to get a shael rune. You can also obtain a shael rune from nightmare countess. You can get a shael rune from the nightmare hellforge quest.
A shael rune requires level 29 to use.
Horadric cube recipes with shael runes
transmute 3 shael runes and a chipped ruby to create a dol rune
transmute normal unique armor, a shael rune, an tal rune, and a perfect diamond to create an exceptional unique armor of the same type