Learn to play Of Knights and Ninjas - medieval card game

About Of Knights and Ninjas, from BoardGameGeek:

Competitive, strategic card game for 2-6 players set in feudal medieval era. GamePlay: On your turn, draw two cards and choose whether to ATTACK another player's kingdom, FORTIFY your own (with a CASTLE or ARCHER), or play a SPECIAL ACTION. When other players attack you, you may play a RESPOND card to lessen the number of gems they steal from you. The first player to own 10 gems wins the game. Of Knights & Ninjas blurs the line between party game and strategy game. Interesting choices of actions as well as responses ensure replayability as every game is unique. Multiple paths to victory require your strategy to constantly be changing. Will you play it safe and fortify your kingdom? Or will you recklessly plunder your way to victory? -description from the publisher