From the brewery:

Collaboration between Tempest and Emperor's is finally upon us. More than a stout, this is beer from another galaxy...Aggresively loaded with chocolate and roasted malts, the base stout spent the best part of a year in Bluegrass bourbon barrels, where the oak, vanilla and bourbon warmth perfectly balanced the roast bitterness and residual sweetness of the stout. As if it wasn't indulgent and complex enough, we rounded things off with a good, good amount of sticky Zahidi date syrup.