Complex sentence: During a garden party, Occula lures Sencho out of sight of everyone else and signals her rebel confederates (by implication Zirek and Meris) to stab Sencho to death.
Split into simpler sentences: During a garden party, Occula lures Sencho away from the festivities. Out of sight of everyone else, Occula signals her rebel confederates (hinted to be Zirek and Meris) to stab Sencho to death.