We examine the impact of deception in Mixed Reality (MR), focusing on how subversive elements affect user behavior and decision-making. In a controlled experiment with 250 participants playing a Whac-A-Mole MR game, we introduced three types of deception attacks: (1) a Physiological Spoofing Attack intended to foster false beliefs about bodily state; (2) a Gaslighting Attack that evokes false interpretations about bodily state by inducing doubt; and (3) a Disinformation Attack that presents false information by mimicking game- and system-level notifications to influence decision-making. We measured the effects on game performance, cognitive load, and behavioral responses. Results reveal that Physiological Spoofing and Gaslighting Attacks led to behavioral adjustments, though these effects diminished over time. Alternatively, false information presented in the Disinformation Attack adversely influenced decision-making. Our findings highlight the vulnerability of MR users to deception attacks and emphasize the need for adaptive security measures to mitigate these risks.