The Classic period lowland Maya used iron-ore mosaic mirrors and deposited mirrors in the burials of rulers and other people. Depictions of mirrors suggest that they were used for scrying, as were mirrors in Mesoamerica at the time of the Spanish arrival. Maya mirror users of this kind were conjurors, who used a variety of other divining and conjuring instruments and materials, including plates and shallow bowls. Three rulers at El Peru-Waka', now called Waka' by researchers at the site, an ancient city in northwestern Peten, Guatemala, were buried with mirrors and associated divining and conjuring materials. Following a brief introduction to the city and its temples, we describe the arrangement of mirrors and associated materials in three royal tombs. We suggest that the mirrors in these tombs were used in conjuring supernatural beings into existence, particularly Akan, a death god and wahy spirit who was a patron of the Waka' realm. We propose that the rulers and mirror conjurors of Waka' were oracles and that Waka' was known for prophecy. References to Sihyaj K'ahk' in text and iconography at Waka', and his association with oracular paraphernalia such as mirrors, lead us to propose a prophetic aspect of the visit of Sihyaj K'ahk' to the site eight days prior to his famous arrival at Tikal in a.d. 378. We suggest that the three rulers we discuss were mirror oracles sustained by the prestige of the prophecy of Sihyaj K'ahk'.