This guide is for buying your first combo. This achievement will come very early on and will more than likely be your first achievement in this game.
During the first 5 minutes of the tutorial you will be learning the basics of attacking. You will be directed to kill 5 enemies to gain 25 experience points. As soon as you kill these enemies your skill book will automatically open for you.
From this point, go down to the advanced moves category and a skill / combo called "Guillotine" will be available for purchase using the 25 experience points you just earned. Go ahead and buy this combo and enjoy your achievement!
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