The devil

Verily, I will mislead them, and surely, I will arouse in them false desires; and certainly, I will order them to slit the ears of cattle, and indeed I will order them to change the nature created by Allah." And whoever takes Shaitan (Satan) as a Wali (protector or helper) instead of Allah, has surely suffered a manifest loss.

[Qur'aan 4:119]

The devil misguides people. He misguides them by taking them out of Islaam and to disbelief. He does so by Waswasa [whisperings]. He puts into the heart the false belief that this life is long and that there is no life other than it. He makes people believe that there is no resurrection and reckoning. He misguides people away from the belief of Oneness of Allaah [Tawheed] to shirk [associating partners with Allaah].

He incites people to make that which is permissible, impermissible and that which is impermissible, permissible.

He incites people to follow their desires and worship him as opposed to obeying Allaah and worshiping Allaah alone.

Anyone who takes the devil as his protector and friend will suffer a great loss. Who takes an enemy as a friend and expects to prosper?

Narrated Ibn Mas`ud: Allah has cursed those women who practice tattooing or get it done for themselves, and those who remove hair from their faces, and those who create spaces between their teeth artificially to look beautiful, such ladies as change the features created by Allah. Why then shall I not curse those whom Allah's Messenger (ﷺ) has cursed and who are cursed in Allah's Book too?

[Sahih Al-Bukhaari - The Book of Dress - Chapter: The lady who lengthens her hair artificially - Hadith No. 5943]