I'm also surprised that why people in this site are spreading rumours that concept of Dashavatar have no base in scripture.
It is true that Lord Vishnu have countless incarnations, also major 24 incarnations but scriptures clearly mention 10 incarnation among these incarnation also. You do not need to go in Todala tantra to get base of this:
Here are some validation of Dashavatar from our scripture:
Padma Purana Uttarkhanda Chapter 229
40-41.Thus the state of the inner controllership of self consists in his being the innermost soul. Matsya, Kurma, Varaha, Narasimha, Vamana, Rama, Parasurama, Krishna, Buddha and Kalki are the ten incarnations of Brahman, the highest soul.
Padma Purana Uttarkhanda chapter 71.26-29
Matsya, Kurma, Varaha, Narsimha,
Vamana, so also Parasurama, Rama, Krsna, Buddha, and after him is said to be (the incarnation of) Kalki. These ten are said to be (Visnu's) ten incarnations on the earth. Merely by (uttering) their names, (even) the killer of a brahmana is always purified. He, by reciting, muttering, meditating upon Visnu's name in any manner, is freed. There is no doubt that he would be Visnu himself.
Agni Purana mentions these as 10 incarnation and describes each in details.
(1) Matsya avatara- fish incarnation (2) Kurma avatara- turtle incarnation (3) Varaha avatara boar incarnation (4) Narasimha avatara- half-man lion incarnation (5) Vamana avatara- dwarf incarnation (6) Parashurama (7) Rama (8) Krishna (9) Buddha (10) Kalki
After describing these 10 incarnation Agni Purana in 3.1 tells
In every cycle (kalpa) and in every era (manvantara) Vishnu is thus born in various forms. It is a sacred duty to listen to the stories of the ten avataras. The listener attains his desires and goes to heaven.
Garuda Purana 1.86.10,11 also gives name of Dashavatar
dharma saṃrakṣaṇārthāya adharmādivinaṣṭaye
daityarākṣasanāśārthaṃ matsyaḥ pūrvaṃ yathābhavat
kūrmo varāho nṛharirvāmano rāma ūrjitaḥ
yathā dāśarathī rāmaḥ kṛṣṇobuddho'tha kalki api [Garud, Pu. - 1.86.10,11]
Similarly Varaha Purana 4.2 also tells about Dashavatara.
matsyaḥ kūrmo varāhaśca narasiṃho'tha vāmanaḥ
rāmo rāmaśca kṛṣṇaśca buddhaḥ kalkī ca te daśa [Varaha. Pu. - 4.2]
Mastya, Kurma, Varaha, Narasimha, Vamana, Parshurama, Rama, Krishna, Buddha, Kalki are the ten incarnations.
Some people also say that it is baseless because chronology is not matching. Although it is true that in refrence to time chronology from Matsya to Kurma to Varaha to Narsimha to .... doesn't matches. But when we talk about Dashavatar then this is the chronology we use. This is already validated by above verses of Purana. But still Lord Krishna in Srimad Bhagwat 10.40 validates this chronology of Dashavatar. He shows Akrura about his incarnations inside water in this chronology and Akrura Prays as: (famously known as Akrura Dashavatar Stuti)
१०४००१७१ नमः कारणमत्स्याय प्रलयाब्धिचराय च
१०४००१७३ हयशीष्णे नमस्तुभ्यं मधुकैटभमृत्यवे
१०४००१८१ अकू पाराय बृहते नमाे मन्दरधारिणे
१०४००१८३ क्षित्युद्धारविहाराय नमः शूकरमूर्तये
१०४००१९१ नमस्तेऽद्भूतसिंहाय साधुलाेकभयापह
१०४००१९३ वामनाय नमस्तुभ्यं क्रान्तत्रिभुवनाय च
१०४००२०१ नमाे भृगुणां पतये द्दप्तक्षत्रवनच्छिदे
१०४००२०३ नमस्ते रघुवर्याय रावणान्तकराय च
१०४००२११ नमस्ते वासुदेवाय नमः सड़्करषणाय च
१०४००२१३ प्रद्युन्मयनिरूद्धाय सात्वतां पतये नमः
१०४००२२१ नमाे बुद्धाय शुद्धाय दैत्यदानवमाेहिने
१०४००२२३ म्लेच्छप्रायक्षत्रहन्ते नमस्ते कल्किरूपिणे
17-18. I offer my obeisances to You, the cause of the creation, Lord Matsya, who swam about in the
ocean of dissolution, to Lord Hayagriva, > the killer of Madhu and Kaitabha, to the immense tortoise, [Lord
Kurma] , who supported Mandara Mountain, and to the boar incarnation [Lord Varaha], who enjoyed
lifting the earth.
19. Obeisances to You, the amazing lion [Lord Nrisimha] , who remove Your saintly devotees’ fear, and
to the dwarf Vamana , who stepped over the three worlds.
20. Obeisances to You, Lord of the Bhrgus [Lord Parashurama] , who cut down the forest of the conceited royal order, and to
the best of the Raghu dynasty, Lord Rama , who put an end to the demon Ravana.
21. Obeisances to You, Lord of the Satvatas [Lord Krishna] , and to Your forms of Vasudeva, Sankarsana, Pradyumna
and Aniruddha.
22. Obeisances to Your form as the faultless Lord Buddha , who will bewilder the Daityas and Danavas,
and to Lord Kalki, the annihilator of the meat-eaters posing as kings. >
As we can see here the order of incarnation we see as
Matsya, Hayagriva, Kurma, Varaha, Nrisimha, Vaman, Parashurama, Rama, Krishna, Buddha and Kalki
Hence this chronology is validated by Lord Krishna himself and this chronology is used to denote Dash Avatars although they are not chronological in refrence with time.
Hence Dasha Avatara concept have validation in Our Scriptures with the popular chronology.
For your question about validation of Todala tantra, it also have base in Shiva Purana. Shiva Purana in 3.16 gives Dash Avatar of Shiva and Shakti.
3.16 Dash Avatar (10 Incarnations of Shiva)
Describing about the ten incarnations and their corresponding power (Shakti), Sutji said- The first incarnation of lord Shiva was as Mahakal and his Shakti was called Mahakali. Lord Shiva took his second incarnation as Tar and his Shakti was called 'Tara'. The third incarnation of Lord Shiva was as Bhuvaneshwar and his Shakti was called 'Bhuvaneshwari'. Lord Shiva took his fourth incarnation as 'Shodash' who was also known as 'Srividdyesh' and his Shakti was called 'Shodashi' or 'Shri'. Lord Shiva took his fifth incarnation as Bhairav and his Shakti was called 'Bhairavi'. The sixth incarnation of Lord Shiva is famous as 'Chhinamastak' and his Shakti by the name of 'Chhinamasta.Lord Shiva took his seventh incarnation as 'Dhoomvan' and his Shakti was known as 'Dhoomvati. The
eighth incarnation was as Baglamukh and his Shakti as Baglamukhi. The nineth incarnation of lord Shiva became famous as Matang and his Shakti as 'Matangi'. Lord Shiva took his tenth incarnation as 'Kamal' and his Shakti as Kamala. If these ten incarnation of Shiva are worshipped along with his ten Mahavidyas then a man attains salvation.
Todala Tantra connects these Dash avatar of Shiva Shakti to Dash Avatar of Lord Vishnu:
Hence as a conclusion concept of Dashavatar have validation in Our Scriptures with its popular chronology.
