You don’t need to be magical to do well in your viva. You don’t need a hidden card with notes up your sleeve or to be able to divine your examiners’ questions before they ask them. You don’t need to be able to perform feats of wonder to astonish all onlookers.
You only need exactly what every good magician has: the right skillset, knowledge and practice.
You can develop all of these over the course of a PhD journey.
No magic words. No hidden talents. Nothing up your sleeve.
You are more than capable of producing what you need at your viva.