Your look turns one creature per round to stone permanently. Once each round, you can choose to look at a creature as a standard action. The creature must succeed on a Fortitude saving throw or be turned to stone.
Creatures can avoid the need to make a saving throw by not looking at you. On its turn, a creature chooses whether it is looking at you normally, averting its eyes, or looking away.
Your opponent can attempt to avoid looking at your face, and instead look at your body, watching your shadow, track you in a reflect surface, and so on. Each round, an opponent has a 50% chance to avert its eyes in this manner, avoiding the need to make a saving throw against your eyes of the basilisk power. However, you gain concealment against that opponent.
An opponent can look away or cover its eyes (such as with a blindfold) so that it cannot see you at all. You gain total concealment against that opponent.