Book of Vishanti vs Book of Darkhold
If you have already watched , Doctor strange in multiverse of madness ,You must have been familiar with words like 'Book of Vishanti' and 'Book of Darkhold'. These books are absolutely powerful enough to do any things we can imagined so far . Book of Darkhold was mentioned in WandaVision TV series and Agents of sheild before also. Let's talk in short about these :
Book of Darkhold : as name suggests it represents the dark and evil way of doing things. With the knowledge of Darkhold, one can acheives his goals and can find solution to any problems but it will cost your soul . It slowly starts to corrupt it's user. Wanda uses darkhold powers to get back her children from another universe and she succeeded to reach to the children by capturing Chavez and defeating Illuminatis . Later ,she realises being guilty as children didn't want her (cause they have their own mother in their own universe).
We clearly see in Wanda's hand , her fingers were slowing changing to black colored. Sinister Strange also uses Darkhold to get Christine back in his universe using Darkhold and his universe got collapsed. Agatha (casted in WandaVision as major antagonist) uses darkhold and her fingers turned into bluish in colour. Thus based on your previous role ,it will effects your body parts like after using Darkhold, Sorcer supreme got Third eye , Scarlett witch got blackish fingers and so on. At the end of Doctor strange in multiverse of madness , Wanda realises how it's corrupt your brain , she destroys every possible copies of Darkhold using magic. After all, it's clear ,whoever you were along with sudden changes in your body parts , it toally corrupts your brain and soul.
Book of Vishanti is also powerful books .After having the knowledge of this book , you can also do impossible things make happens and can find solution to any sorts of problems . In this books ,it is brighter way and it won't cirrupt your minds and brains. It rather makes you more powerful as well as purifies your brain.
Our main universe Doctor strange who was in Illuminati universe said Illuminati members that they should let help him to get Book of Vishanti but they denies. illuminati thoughts they will easily outstands Wanda and they thinks Doctor strange will be the problems. Since Wanda already killed Illuminati and by any sorts ,Doctor strange alongs with Chavez went to reach juntion point of Universe also known as 'Library of Multiverse " path lead by Palmer of Illuminati universe and Wanda followed the same path. Eventually when Doctor strange was almost reached to get Book of Vishanti ,Wanda destroyed it using her full potential before Doctor strange do anythings. Thus , we never see the true potential of 'Book of Vishanti' . It's clear that Book of Vishanti was also solution to every problem.
In Conclusion : Book of Vishanti and Book of Darkhold can be used to find solution to any problems. Where it cost soul and corrupts your minds in Book of Darkhold ,it purifies your mind and is brighter way to find solution with 'Book of Vishanti'.