Respec

You can respec your character at Mr Martino. You receive one respec at level 11 and another at level 61. You also receive one respec when you kill Sylfir, the uber end boss. There is no way of getting more free respecs after that. You will have to create a new character. Orb of Despair let you respec your character but they rarely drop.

Once you activate a respec, you can change it unlimited times as long as you stay in town, the Training Zone and the PvP area. You can test various builds thoroughly without any rush (you can even exit the game and re-enter later) but as soon as you leave those zones, you are committed to your build.