The study of generation, physics and mitigation of runaway electrons (RE) is very important, as the RE beam can severely damage plasma-facing components at tokamaks. The GOLEM tokamak is an optimal environment for generating runaway electrons due to the low plasma density and high electric toroidal field. Especially with the recently developed enhanced plasma regime operation with much longer discharges (up to 40 ms) and higher runaway electron currents. Usually, runaway electrons are measured indirectly, typically by cyclotron radiation or by HXR radiation emitted when the RE beam strikes plasma-facing components. A new diagnostics of runaway electrons is designed. This diagnostics will measure runaway electrons directly in the tokamak chamber. It is an unusual approach, which can potentially give us more precise information of RE energy distribution, pitch angle and other parameters. The probe is formed by a cascade of very thin scintillation crystals for special energy resolution treatment. With a collimator and a rotary head, various positions and angles can be measured. The signal is transferred by optical fibers and amplified by silicon photomultipliers. The probe design will be presented. The first measurement results might also be included, provided the commissioning of the diagnostics proceeds as planned.