Praise be to Allah, and peace and blessings be upon the Messenger of Allah and his family.
The Hadiths that the Shi`ah narrate exclusively are not considered; because they do not give attention to the conditions of an authentic Hadith, rather their deliberate lying is well-known.
Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
"As for Hadith, they are among the people furthest from knowing it: neither its chain of transmission nor its text, nor do they know the Messenger and his conditions. Hence, when they transmit anything from the Hadith, they are among the most ignorant of people concerning it. And any book they find that agrees with their desires, they transmit it, without knowledge of the Hadith." End quote from "Minhaj As-Sunnah" (6/379-380).
However, it has been established that there will be an increase in deaths in the last days, and this has been mentioned among the signs of the Hour, without any mention of this alleged ruler, neither closely nor distantly.
Al-Bukhari narrated in his authentic collection (3176) that `Awf ibn Malik said: I went to the Prophet (may Allah's peace and blessings be upon him) during the battle of Tabūk, while he was sitting in a leather tent. He said: "Count six signs that indicate the approach of the Hour: my death; the conquest of Jerusalem; a plague that will afflict you (and kill you in great numbers) as the plague that afflicts sheep; the increase of money to such an extent that even if one is given one hundred dinars, he will not be satisfied; an affliction which no Arab house will escape; and a truce between you and Banu al-Asfar, who will betray you and march on you under eighty flags. Under each flag will be twelve thousand soldiers."
And his saying: "mawtan" means a death that occurs frequently.
It appears that this severe death will occur among people due to the trials that happen in the last days.
Also in Musnad (16964) from the Hadith of Salamah ibn Nufayl As-Sakuni (may Allah be pleased with him), the Messenger of Allah (peace and blessings be upon him) said in a Hadith about the conditions of the last days: "And you will come in groups, some of you will destroy others, and before the Hour there will be a severe death, and after it years of earthquakes." The Hadith has an authentic chain of transmission, as mentioned by the researchers of the Resalah edition.
And from Abu Hurairah: The Prophet (peace and blessings be upon him) said: "The Hour will not come until knowledge is taken away, earthquakes increase, time passes quickly, trials appear, and there will be much Harj – and it is killing, killing – until wealth among you will become abundant and overflow." Narrated by Al-Bukhari (1036).
And from `Aishah: The Messenger of Allah (peace and blessings be upon him) said: "In the last days of this nation, there will be sinking into the earth, disfigurement, and stones raining down. I said: O Messenger of Allah, will we be destroyed while there are righteous people among us? He said: Yes, when immorality is rampant." Narrated by At-Tirmidhi (2185).
Al-Albani (may Allah have mercy on him) said: "The Hadith has many supporting evidences that testify to its authenticity." End quote from "As-Silsilah As-Sahihah" (4/393).
Perhaps due to the trials and killings, the number of believers will decrease, as reported by Muslim (2945) from Umm Sharik, that she heard the Prophet (peace and blessings be upon him) say: "People will flee from the Dajjal into the mountains." Umm Sharik said: O Messenger of Allah, where will the Arabs be at that time? He said: "They will be few," and in another narration by Ibn Majah (4077): "Umm Sharik bint Abi Al-Akr said: O Messenger of Allah, where will the Arabs be at that time? He said: They will be few at that time, and most of them will be in Jerusalem, and their leader will be a righteous man."
Sheikh Muhammad ibn `Ali ibn Adam Al-Ethiopi (may Allah have mercy on him) said:
"(Layafirran) means: By Allah, people will definitely flee (from the Dajjal into the mountains) to escape his trial. Umm Sharik (may Allah be pleased with her) said: O Messenger of Allah, where will the Arabs be at that time? At-Tibi (may Allah have mercy on him) said: The 'fa' in the response to the omitted condition is as if this is the state of the people, then where are the mujahidin in the cause of Allah, those who defend the sanctity of Islam, those who prevent the enemies of Allah from attacking its people, so he indicated it with 'fa'. The Prophet (peace and blessings be upon him) said: "They," meaning the Arabs at that time, "will be few," meaning they will not be able to handle it, and Allah knows best. End quote from "Al-Bahr Al-Muhit" (44/667).
And Allah knows best.