Juturna

Juturna was the Saddle Arabian assassin sent by the Sultan to murder Twilight Sparkle. She arrived in Canterlot as part of Thakr's entourage, though he did not know her intent. This derailed the scheduled peace talks and further enflamed the Equestrian nation's budding xenophobia.
Lozenge witnesses these events out of order, but later pieces together the proper sequence.