Salvations from the Four Minim
There are many segulos in the merit of taking the four minim.
The Yerushalmi (quoted in the Rosh סוכה פ"ג כ"ו, and see also Maharsha, Succah 38a) writes that when we shake the lulav during Hallel, it shakes up and weakens the מקטרגthe malachim who speak against us.15
Reb Mendel of Riminov zt'l )מנחם ציון, האזינו( says, "During Succos, we take the four minim, like brooms. With them we sweep away all the resha'im of the world. For, in every generation, the seventy nations of the world are mikatreg against us. This is so true; it is like I see it with my eyes. Every Yid creates the seventy nations himself [with his aveiros], and we must overcome them and negate them. Therefore, we take the four minim, and we fight with the mikatrigim who cause us tzaros. The four minim are our weapons, as the Tikunei Zohar (29a) tells us. We wave the four minim back and forth, so that wherever there is a mikatreg who speaks
15. Rosh Hashanah and Yom Kippur have passed, and people think that the days of judgment are over, but it isn't so. As we will explain, Hoshana Rabba is still an integral part of the days of judgment. Our lives, successes, parnassah etc. are still being determined, even if we are unaware of it. Therefore, Hashem gave us the mitzvah to shake the lulav on Succos, as that silences the mikatrigim, and they won't speak against us on Hoshana Rabba. With this mitzvah, we prepare and protect ourselves from a harsh judgment. People perform this mitzvah, and often have no idea that they are being judged. We can compare this to a child who is blissfully playing on a rooftop, unaware that there is no gate there, and that he is in great danger. But people below are aware. They place cushions on the ground, around the house, and call Hatzalah to save the child. Similarly, many people are unaware that we are still in the judgment, and that our lives, our parnassah, our health, etc. are on the line. It is a critical time, but many aren't aware of it. Hashem gave us a mitzvah to shake the lulav to silence the mikatrigim so that we will have a good judgment. With this mitzvah, Hashem protects all of us, including those who aren't aware of what is at stake.