Well I did take into consideration all your warnings and I won't prepare for it. Instead, I'm going to work my brain a bit with those cubes. Going into practice mode and I'm going to strive to get 100% (got 80% max once, was so happy). There shouldn't be anything wrong with doing so vision exercises to stimulate my neurons
On-topic: In my opinion, the most important thing you should have is the confidence in yourself. If you go to FEAST with thoughts like : "my parents will be so mad if I fail", "my whole life depends on this test", you are 90% sure to fail. Like someone said on this thread, he started bad, but then chilled, found his happy place and managed to go through with it. I'm going to try to do the same.