Source: Mahabharata Vana Parva – Tirtha Yatra Upa-parva, Mahabharata Tatparya Nirnaya Chapter 22
The avatara of Lord Krishna and the Pandavas was with the specific agenda of destruction of evil on earth and reduction of the population. At that time, the land was occupied by crores and crores of Rakshasas. The various incidents in the Mahabharata was a play of the Lord to create situations to facilitate destruction of this evil.
The vanavasa of the Pandavas was also one such excuse to ensure many evil Rakshasas and their followers were eliminated. During the 13 years of the exile, Bhimasena and Arjuna performed a lot of such work.
When Arjuna had gone to Swarga Loka to spend time with Indra, the remaining Pandavas undertook a Tirtha Yatra. As part of this yatra, they reached Uttara Badari Kshetra. Once, when they were in Badari, Bhimasena and Draupadi were engaged in a conversation. At the same time, Garuda had visited a nearby lake and picked up a snake for his meal. The sheer force with which Garuda swooped down and subsequently lifted up caused a huge wind which caused a few “Sougandhika” flowers to come off. One such flower, which had a golden hue, flew and fell near Draupadi. Greatly impressed by the flower, she asked Bhimasena to get her some more flowers.
Bhimasena immediately proceeded towards the lake. On the way, he killed numerous evil Rakshasas who tried to fight him in the form of wild animals. Eventually, he reached the lake. Just as he was about to get into the lake and pick up the flowers, a huge army of Rakshasas stopped him. These Rakshasas were known as “Krodhavashas” and were working under the leadership of a evil Rakshasa called Manimanta and were also under the supervision of Kubera. Kubera is a dikpalaka and is also the God of wealth. Manimanta and Kubera were great friends.
Bhimasena was challenged by the Rakshasas not to pluck the flowers. They asked him to request for it. Bhimasena sighted various shastras and made it clear why he reserves the right to take the flowers. The Rakshasas tried to engage him on a debate on philosophy and failed. They then attacked him. Crores of Rakshasas were killed by Bhimasena. A few who lived ran away and informed Kubera. The God of wealth, upon hearing that Bhimasena had caused this state, chose not to react. Meanwhile, Yudhishthira saw some omens related to war and reached the lake. He saw the havoc that his brother had caused. Bhimasena then picked up numerous Sougandhika flowers and returned. Draupadi was very pleased.
After a few days, there was once again a huge wind which caused a few “Panchavarna” flowers to come off from the house of Kubera and landed near Draupadi. The Panchavarna flowers were composed of 5 bright colors and were very attractive. Draupadi once again requested Bhimasena to fetch her a few flowers. Immediately, Bhimasena proceeded towards the palace of Kubera. This time, Bhimasena was opposed by Manimanta himself along with his huge army of 3 Padmas (each Padma is multiple crores). Bhimasena easily defeated all of them and killed them. Their leader Manimanta was also killed.
Upon hearing this news, Kubera got very upset and approached Bhimasena. There was avesha of an asura on Kubera and hence he ventured out to face Bhimasena without thinking about Dharma and even his capacity. At the same time. Yudhishthira sensed the absence of Bhimasena. Enquiring Draupadi, he realized where Bhimasena was and asked Ghatotkacha to take him there. Yudhishthira reached the place just as Kubera was to attempt the foolish act of attacking Bhimasena. The asura avesha of Kubera reduced a little at that moment and he offered his friendship to Bhimasena and Dharmaraja. He even offered his palace to them. Pandavas spent around 5 years in Kubera’s home and the homes of other devatas there.
Thus, the Sougandhika flower incident and the Panchavarna flower incident provided two situations to Bhimasena to destroy crores and crores of Rakshasas thereby reducing evil on earth. Of course, this service to the Lord culminated in the Kurukshetra war where once again Bhimasena performed his service to Lord Krishna by killing crores of people.