Here are the passages in the Zohar that refer to the star of Yaakov:
ZOHAR [some relevant commentaries in brackets]
At 66 years Melech Hamoshiach will be revealed in the land of the Galil [Moshiach ben Dovid; Galil Elyon. Sulam: Moshiach ben Yosef] and when a star on the East side [tiferes] will swallow seven stars on the North side [bina], and a flame of black fire will be hanging in the firmament 60 days, and wars will be awakened in the world on the North side, and two kings will fall [Sulam: one from the nations and one from Israel, Moshiach ben Yosef] in these wars, and the entire world will come together against Bas Yaakov [the Jewish nation] to push her from the world. Of this time it is written "and it is a time of trouble for Yaakov and from it he will be saved". At that time all the souls [nefashos] in the treasury of souls [guf] will be finished and needing to return to be renewed, and the sign for you is all the souls [kol hanefesh] that came to Yaakov from mitzrayim, etc., 66 souls.
A pillar of fire will be seen standing from above to below 40 days. All the nations will see it. At that time Melech Hamoshiach will awakedn and go out from Gan Eden, from the place called Kan Tzippor, and will be revealed in the Galil. On that day that Moshiach goes out from there, the entire world will shake and all world will hide themselves in caves and clefts in the rocks, and they won't think to be saved. [...] After 40 days that the pillar will stand from the earth to the heavens in the eys of all the world the Moshiach will be revealed. A star will arise from the East side, flaming with all colors, and 7 other stars will go around this star and make a war with it on all sides 3 times a day for 70 days, and all the people of the world will see.
That same star will make war with them with blazes of fire and flaming and sparking on each side, and it will hit them until it swallows them each and every night, and then in the day it returns and expels them, and they make war in the eyes of the whole world.
After 70 days, that star will be concealed and Moshiach will be concealed for 12 months and the pillar of fire will return to the way it was before and in it Moshiach will be concealed and that pillar will not be seen.
[...] one awesome star will awaken in the middle of the firmament like Argaman flaming and sparking in the day in the eyes of the whole world. A flame of fire [S"M] will arise on the North side in the midst of the firmament and these will stand one opposed to the other for 40 days and the star and the flame will make war in the eyes of all, and the flame will spread out with a burning of fire amidst the rakia from the North side. Numerous rulers and kings and nations and peoples will be terrified of this. Then a star will arise from the South side [the light of Chesed] and will take control of the flame and the flame will be consumed slowly in the firmament, in front of that star, until it won't be seen at all. Then the star will paths in the firmament in 12 directions. These lights will stand in the firmamanet for 12 days. After 12 days all the people of the world will tremble and the sun will go dark for half a day, like it went dark on the day the Bais Hamikdash was destroyed, until the heavens and the earth won't be seen.
R' Elazar and R' Abba were sitting one night. When it got dark they entered the garden which is on the sea of Teveria. In the midst of this they saw two stars travelling from opposite directions, and [the stars] ran into each other and disappeared.
Then the 7th window will open in the entire world, and it's star is "kochav Yaakov", and this is the one about which Bilaam said "a star shoots forth from Yaakov", and this star will be luminous for 40 days and 40 nights. When Melech Hamoshiach will be revealed, and all the people's of the world will be gathered to him, then the verse will be fulfilled which states (Yeshaya 11:10): "the root of Yishai, which stands as a banner for peoples, to him shall the nations inquire, and his peace shall be [with] honor."
We have learned that in the future the Holy One will rebuild Yerushalyim and show one steady star, flashing with 70 pillars of fire, and with 70 sparks which illuminate (receive light) from it in the middle of the sky. There will be 70 other stars which are commanded and controlled from it, and they will illuminate and flame in the sky for 70 days.
On the 6th day, the 25th day of the 6th month [Elul], the star will appear. It will be gathered on the 7th day, at the end of 70 days. [It will be concealed and will not be seen]. On the first day it will be seen in the city of Rome. On the same day, 3 supernal walls [power of the 3 impure klipos] of that city of Rome will fall and a great heichal [the mate of the S"M] will fall. The ruler of that city [the S"M] will die. Then the star will spread out to be seen in the world. In that time strong wars [among the goyim] will awaken in the world on all 4 sides and emunah will not be found among them.
In the middle of the world, when that star will shine in the middle of the sky, a great king [the force of the S"M and supernal sarim will overpower him] will arise and rule the world, and his spirit will gain pride over all the kings and he will awaken a war on 2 sides, and he will become strong against them.
On the day that the star will be concealed, the Holy Land will quake [after 70 days] 45 miles around the place of the Bais Hamikdash, and one cave under the ground [sod malchus, and from there will awaken the gehinom] will be revealed. From this cave will come out a strong fire to burn the world. From this cave a supernal branch will grow and it will rule over the whole world, and to it will be given the malchus. The supernal holy ones will gather to it. Then Moshiach will be revealed in the entire world and malchus will be given to him.