Win a long war of attrition. Before getting into the fight, have a -2 damage taken buff for one fight, from one of the nodes on the map (sacrificing a rare card).
The “Arcane Knowledge” card, despite its current bugs, has a use to make basic shields and basic attacks free (so you can spend mana on draw). Abusing the armor buff, you can cast it without taking self-damage.
I won on my first try, with a bad matchup, a deck oriented to abuse poison stacking - that doesn’t work too well when the elf purges all debuffs (stuns help but are unreliable). But you can still do that effectively if you also have the epic card that prematurely triggers and removes all poison as a payoff card.