Is Black Magic Practiced in Thailand nowadays?

Not really, but many Thai people still believe in so called Black Magic, in the supernatural and superstition and buy different amulets.
Evidence of belief in black magic is evidenced by a rather strong belief in ghosts. This is easily seen around the country in the form of spirit houses.
A spirit house is raised up off the ground – usually at least a meter high, often two meters high – and is a place for the evil or bad spirits to rest so they don’t bother anyone on the property.
Many people make offerings to the spirits at these houses or shrines – of soda, fruit, water, other beverages, cigarettes, and other things. It is not unheard of to pass a spirit house on the side of the road that is covered in red Fanta soda bottles and cans. Anything to do with the spirit baby – Kuman Thong – often is predominantly covered in red Fanta offerings. Spirit houses may have monks, Kuman Thong, Kwan Yin, Nong Kwak, Luang Phor Tuad, Luang Phor Klai, Ganesh, Shiva, Rahu, or other respected or feared deities.
A yant (yan, yantra) is a magical phrase or spell used to imbue something with supernatural power. Often times Pali language symbols are used. Pali is the language used during the Buddha’s time in Northern India. There are yant tattoos, yant flags, yants on takrut amulets, and yants on the back of Jatukam Ramathep amulets from Nakhon Si Thammarat, and many other amulets. Yants can consist of any combination of Thai and Pali words and symbols, star patterns, patterns monks create, geometric shapes and patterns, chinese zodiac symbols, and images of Rahu or other demons or deities.