Privateer Press have posted a preview of the Trollblood Runebearer Warlock Attachment for Hordes.
From their website:
Some of the most learned trollkin runescribes choose to accompany their leaders into battle. Carrying the sacred tablets of their kriel, runebearers are capable of amplifying the Dhunian gifts of trollkin warlocks. The glyphs glow as the runebearer speaks them aloud, easing their warlock’s use of their fury-driven prayers and sorcery.