<p>In this paper, the authors assess a small rock cut failure in a rather jointed slate rock mass in northwestern Spain occurred after a rainfall event. A non-standard failure mechanism was observed to produce a toppling failure partially induced by a sliding failure in a lateral zone of the slope. The failure generated a small landslide mobilizing about 300 m³ of rock that closed the access road to a hydropower plant underground facility for a few days. To investigate this failure mechanism, a detailed field survey was conducted to characterize the regional geology, discontinuities, and photogrammetry, alongside a series of laboratory tests to determine intact rock and joint geomechanical properties. Based on these observations and tests, a wedge sliding failure was initially identified; however, further kinematic and limit equilibrium analyses revealed a more complex wedge-toppling combined failure mechanism. The mechanism is also noteworthy in that the kink-banding associated with the slate in the rock mass plays a non-negligible role in the development of the rock slope failure. Additionally, the analysis is presented in the context of combined failure mechanism analysis, specifically, wedge and toppling failures, which can contribute to a better understanding of rock-mass slope failure phenomena and could be also useful for designing future protection measures.</p>