Jund is a creature-dense midrange deck, so Sunspine Lynx comes in as a big body that also pings them for nonbasics (they run plenty: Overgrown Tomb, Stomping Ground, Blood Crypt, Blazemire Verge) while shutting off any incidental lifegain. Strategic Betrayal is an edict, so they choose which creature to exile and will usually give up a cheap body like Greedy Freebooter or Callous Inspector rather than Smaug the Magnificent or The Sackville-Bagginses. Its real value is exiling their graveyard, which blanks Lively Dirge reanimation and any value they've built up there. Flamecache Gecko and Stinging Vitriol are the weakest cards against a deck that isn't relying on discard-sensitive hands or small pings. Keep Master of Barbs and Iridescent Vinelasher as they punch well into their creature mirror.