The character who carries this most potent of potions can take a swig when he or the unit that he is with is about to take a Leadership test. The character's Leadership value is immediately boosted to 10 when the test is taken. Unfortunately the effect of the brew is but momentary and the character's Leadership value returns to normal thereafter. Guzzla's Backbone Brew can only be guzzled once - so you get just the one use - but the full Leadership value of 10 applies to any re-roll you might be entitled to should you be unfortunate enough to fail the first time. This bonus Leadership is modified by combat results, etc, as normal.