You have recurring visions that leave you with the unshakable feeling that there's a darkness hunting you. In an attempt to protect your tribe from whatever is after you, you flee Joraga territory. Not far outside the safety of the forest, you detect the unmistakable scent of vampires.
The Vampire Stalkers' deck is a Vampire tribal deck with some creatures that are stronger while an opponent has 10 or less life. Their base stats are subpar, however, with several 1/1s for one and 2/1s for 2, particularly when compared to Nissa's creatures. Nissa's cheapest creature, Nissa's Chosen, already outclasses all of the opposing creatures except Bloodrite Invoker, which it still trades with. Furthermore, unfortunately for the Vampires, Nissa has repeatable lifegain in her deck from the Grazing Gladeharts, which can make it pretty difficult for the Vampires to get her to 10 in the first place.
The duel is almost impossible to lose if you get a reasonable draw and just leave your creatures back to block. The Vampires do have a couple of removal spells, but even if they draw both of them early, all Nissa needs to do is play a third creature and she gets board control. Once you have full board control, you can push your advantage by attacking with Charging Rhino, which either gets through or forces a chump block (since it can't be blocked by more than one creature, and none of the Vampires' creatures can challenge it), while leaving your other creatures back to block.
The only creature the opposing side has that can pose any sort of threat if Nissa has creatures of her own out (and isn't at 10 or less life) is a Bloodrite Invoker, which can be dealt with by using Wild Instincts to have any of Nissa's creatures fight it. Its ability is quite slow, costing 8 mana per activation, so by the time the opposing side has enough lands to activate it you should either already have a Wild Instincts or at least be able to mostly ignore the Bloodrite Invoker due to Grazing Gladehart triggers.