This is Wms gaming Mystical Unicorn slot machine $ bet Huge Mega Big Win bonus round. I haven't. Mystical Unicorn Slot Bonus Round Big Win Jackpot Free Spins. You can play all our online slot machines free for fun or with real money to win HUGE. Mystical Unicorn is an exciting free-spin based slot game on a 5x4 reel array, powered by our G+ Deluxe game engine. Coming from our Williams game studio.