This is how it works. The basics are very similar to playing a rogue except that there is (currently) no auto-attack. You have a bar of chi that mimics the rogue energy bar. You also have a bar with slots for four light orbs and four dark orbs. The basic level 1 attack, Jab, consumes 40 chi (out of 100) with every shot and grants you both a light orb and a dark orb.
Also at level 1, you get an attack that consumes one light orb that does twice the damage of Jab. If the target is over 50% health, it inflicts three times the damage of Jab. At level 2, you get a kick that inflicts three times the damage of Jab and consumes two dark orbs but returns one if the kick kills the opponent.