With Key Mode activated on Orchid, any note you play on the keyboard will automatically generate a chord that fits within that key.
Press the Key encoder to enable or disable Key Mode, then turn the Key encoder to select your desired key. If you select Bm, all the keys on the keyboard will generate chords that are in the key of B minor.
When Key Mode is enabled, your selected key will display on the screen, and an LED will show next to the Key encoder.