Shavuot Chasidus

Netivot Sholom on Zman Matan Torateinu
"The words of the LORD are pure words, silver purged in an earthen crucible,
refined sevenfold (Psalms 12) There is a secret contained in this verse in that it alludes to the revelation of the Torah in which which the Israelites heard these pure and silver purged words such that they became refined seven-fold through them. These are equivalent to the days of the counting of the Omer (7x7). The Jewish people themselves became refined and tested during this period. Only when they reached that level of purification did they merit to receive the Torah.
The preparation that we found in regard to Shavuot is unique in the Torah among all the various holidays. First, we have this notion of a lengthy counting and within that, the requirement for there to be no lacking in the counting. Then, we have the 3 days of separation, which just like all manners of the revelation of Torah is eternal and applies every year. All of this is connected to the essence of the holiness of the day which is awe-filled. This is like that which the Ari states that Shavuot operates on a very high spiritual plane moreso than all the other holidays. This is also stated by Reb Baruch of Mezhbiz who declares Shavuot even more grand than Rosh Hashanah. On Rosh Hashanah, we're judged for the material matters of the world but what really do those material things matter in the scope of Shavuot, where we're judged for the whole year on our spiritual essence. The source for this comes from the siddur of Reb Kopel of Likova who quotes in his siddur the rabbinic teaching that on Shavuot, we're judged regarding the fruit of the trees. The tree is a hint at God who is known as the Great Tree and the fruits are the souls of Israel. On this holiday, our souls are judged based on our spiritual growth...
There is some amount of judgement based on past events and some based on future events. This is what the Toldot Yaakov Yosef wrote in Parshat Pinchas regarding the teaching of the sages that 3 books are opened on RH: one for the fully righteous, one for the fully wicked, and one for the in-betweens. Every Jew has these books opened up in front of them and they have a clear choice and agency to write themselves in any of teh books. It's up to each of us to decided how we're going to be in the year to come. Are we going to fully give ourselves over to God or God forbid, the opposite. Based on this coice, our judgement is written.
This same teaching applies to Shavuot in regard to that which you are accepting upon yourself for the future. We know this from the teaching of the Or Hachaim who writes that Shavuot comes from the language of shevuah-oath. It is a day of 2 oaths. There is the oath that the people swear to God to protect the Torah and that they will be faithful until their last breath. There is also the promise that God makes to us that God won't renege on God's deal and choose another nation. This is the essence of the oath of faiths that we all make.
This is why we have such a lengthy preparation process that contains within it this 7 fold process. As it is written in the Beer Avraham (Va'era) in regard to the Exodus from Egypt: there was a sullying of our attributes there such that until they were detoxed, we couldn't merit redemption. Only by the power of our faith could that purification and subsequent redemption happen. So too, in order to receive the Torah we also need to go about this cleansing process. This is like that which R' Chaim Vital wrote "the purification of our character traits and attributes becomes the vehicle through which the Torah descends to us." Only a person who has performed this is worthy.
Therefore, we need to work very hard during this period of the Omer as preparation and purification of our attributes on the level of a seven-fold refinement. Even with that, after everything a Jew does during this period, going to all the high levels of work necessary, can anyone really get to the necessary level of revelation? Given that this day is considered like a wedding between God and Israel, the greatest form of cleaving, who among us can get there? As the Kedushat Levi wrote, even if a person prepared the whole year, it wouldn't be enough! His answer is that you can...in that which you renew and prepare yourself for the future.
This is why it's written in the Torah regarding the Omer that the day after Shabbat, you count 50 days. This is the process of refining yourself seven-fold. But even so, it's not quite enough for revelation. It's only when "you offer a new sacrifice to God." This is akin to acknowledging that in your future, you will offer a sacrifice of renewal to God. This is what Reb Levi said was meant by the phrase, "and I will bear you on eagle's wings." An eagle is called a nesher because it lets go-mashir its feathers as it gets older and regrows new ones as it's written in Psalms 103 "so that your youth is renewed like an eagle."
Based on this, a person needs to slough off of themselves their past so that they can renew for their future. This is the sacrifice the Torah is alluding to on Shavuot when it speaks about a mincha chadasha, a new sacrifice. This is supported by what my great grandfather wrote on the verse "a wicked person should leave their path." It's not that they should fix their path but they should leave it totally. What help to him is there if he just fixes the thing that he's come to know. He needs to find a totally new path. This is what a Jew can find on Shavuot.
It is brought by the Ari regarding the sanctity of this night, the meaning of a person's life is dependent on it. The hours of Shavuot are some of the most significant spiritual hours of the year. They come from the power of the verse, "I will sprinkle upon you purifying waters and you will be purified." Just like this is happening in the supernal realms, it is also happening in our world to each of us. God gives us these waters in which we can purify ourselves if we can just do our part to prepare for it by offering renewal.