Guild Wars 2

Anyone know how to make Minor Rune of Hoelbrak?

Some runes and sigils are not craftable, just like the minor rune of hoelbrak. You usually obtain them by salvaging them off armor/weapons or from the mystic forge.

So you can either salvage them from a weapon that has it on them or throw 4 other minor runes into the forge and hope for the best. But as they only cost around 20 copper on the TP, i would buy one there.