seeing through the eyes of scriptures
"In Lord Narasimha a, Rämacandra, and Krnsa the the six transcendental opulences are
perfect and complete. They are the parävasthas (most important forms of the Lord). From
Him (Krsna) they are manifested as lamps are lighted from an (original) lamp.
This vers is found in Padma Purana
so in Ramayana it is narrated: Rama and Lakshmana are captured by the rakshasa Mahiravana (or Ahiravan), brother of Ravana, who held them captive in their palace in Patala (or Patalpuri) --the netherworld. Mahiravana keeps them as offerings to his deity. Searching for them, Hanuman reaches Patala, the gates of which are guarded by a young creature called Makardhwaja (known also as Makar-Dhwaja or Magar Dhwaja), who is part reptile and part Vanara.
The story of Makardhwaja's birth is said to be that when Hanuman extinguished his burning tail in the ocean, a drop of his sweat fell into the waters, eventually becoming Makardhwaja, who perceives Hanuman as his father. When Hanuman introduces himself to Makardhwaja, the latter asks his blessings, but fights him to fulfill the task of guarding the gate. Hanuman defeats and imprisons him to gain entry.
Upon entering Patala, Hanuman discovers that to kill Mahiravana, he must simultaneously extinguish five lamps burning in different directions. Hanuman assumes the Panchamukha or five-faced form of Sri Varaha facing north, Sri Narasimha facing south, Sri Garuda facing west, Sri Hayagriva facing the sky and his own facing the east, and blows out the lamps. Hanuman then rescues Rama and Lakshmana. Afterwards, Rama asks Hanuman to crown Makardhwaja king of Patala. Hanuman then instructs Makardhwaja to rule Patala with justice and wisdom.
So the question I was asked was how can Hanuman manifest the face of Lord Varaha , Sri Narasimha ,and Sri Garuda and Sri Hayagriva and his own .If Hanuman can manifest Sita Rama in his own heart and rip open his chest and so powerful as a child he was about to eat the sun.What is impossible for the Supreme Lord and his devotee Hanuman. Pure devotee sometimes manifest the supreme Lord ,so as this was for the service of Lord Ramachandra and of course all lila that Hanuman rescued his Supreme Lords from Patala .Nrsimhananda Brahmacari during Lord Caitanyas lila was a great Narasimha bhakta so much so Lord Narasimha personally manifested and talked to him on a daily basis. In SB 5.18.canto Sri Prahlada Maharaja also prays for this avirbhava that Lord Narasimha may constantly appear in his heart and drive away his ignorance :
āviḥ-āvirbhava— please be fully manifest ;In Lord Caitanyas lilas , Lord Caitanya was always manifest when ever mother Saci cooked and Lord Nityananda Prabhu did His kirtanas .So for Hanuman to perform such pastimes where He manifests the face of Lord Narasimha, Lord Varaha and Sri Garuda and Hayagriva is just the Lords pastimes in Jana loka sages meditate on the Supreme Lord in various forms and He manifests these forms.
Sri Hanuman also once manifested a 7 arm form and a 11 arm form, sometimes a giant form . Well know Hanuman could have single handedly killed Ravana and his whole army , but that was not Lord Ramachandras plan .He defeated with ease all Ravanas soldiers and put Ravanas palace on fire , the ruins of Ravanas palace is still there in Sri Lanka .
In the Puranas there are many prayers to Panca Mukha Hanuman as this form drives away ghosts big time:
there is there is at least 5 different kinds of Hanuman Kavachas :
Panchmukhi Hanuman Kavacha
Hanuman Chalisa by Sri Tulsi das Goswami is also a Kavacha
Hanuman Kavacha from Brahmanda Purana
Panchamukha Anjaneya Stotra
Ekadasa Mukh Hanuman Kavacham
I hope this helps understand this subject