All About Gog and Magog, the Anti-Christ, and the Beast
Question

Can you give us an idea about the Dajjal, Al-Dabbah and Yajuj and Majuj?
Praise be to Allah.Three major signs of the Day of Judgement 
There follows a brief description from the Quran and authentic Sunnah narrated from the Prophet (peace and blessings of Allah be upon him) about Gog and Magog, the Antichrist, and the Beast which are three major signs that will precede the Hour and will come at the end of time just before the Day of Resurrection.
The Antichrist (Al-Dajjal)
The Dajjal – a man created by Allah, who will appear at the end of time because of something that makes Allah angry. He will spread corruption on earth and will claim divinity, calling on people to worship him. 
People will be tested by the extraordinary powers that Allah will grant him, such as causing rain to fall, reviving the earth with vegetation and extracting the treasures of the earth. 
The Antichrist will be a young man with a ruddy complexion, short of stature, with curly hair. He will be one-eyed; his right eye will be flat and his other eye will have a thick piece of flesh over it. Written between his eyes will be the word “Kafir” (disbeliever). Most of those who follow him will be Jews. He will meet his end at the hands of ‘Isa ibn Maryam (Jesus the son of Mary) who will kill him with a spear in Lod, which is in Palestine.
Gog and Magog
Yajuj and Majuj are two disbelieving tribes from among the sons of Adam. They have wide faces and small eyes. They used to spread mischief on earth, so Allah gave Dhu’l-Qarnayn the power to build a barrier to detain them. They will keep on digging at it until Allah gives them permission to come out at the end of time, after ‘Isa (peace be upon him) has killed the Dajjal. 
Gog and Magog will emerge in huge numbers and will drink up the lake of Tiberias (in Palestine). They will spread mischief on earth and no one will be able to resist them. Jesus (peace be upon him) and the believers with him will take refuge in Mount Tur until Allah destroys Yajuj and Majuj by sending worms that will eat their necks. Then Allah will send rain to wash away their bodies into the sea and cleanse the earth of their stench.
The Beast
Al-Dabbah is a great creature which Allah will cause to emerge when the people become corrupt. It will speak to mankind and exhort them, having the ability to reason and speak. It will make marks on the people’s noses which will distinguish the believers from the disbelievers. (For more, please see Ashrat al-Sa’ah by Yusuf al-Wabil or al-Qiyamah al-Kubra by ‘Umar al-Ashqar).
The responsibility of the Muslim is to believe in what was narrated from Allah and His Messenger (peace and blessings be upon him). How many wondrous and strange things has Allah created in this world, which speak of His might and power, may He be glorified and exalted.
And Allah knows best.