^Like I said de Plasencia and there's a few. Chirino wrote about bits and pieces of Filipino religion (mostly biased and kind of offensive, Chirino obviously was writing how they pretty much eradicated the mainstream practices while they converted them to Catholicism, so majority of what you'll find are really scraps but it's interesting to hear how they practiced it from primary sources, being that Jesuits like Chrino actually went to the boonies). Jocano's Mythology I'm sure has more, I've only seen parts online, but Jocano covers a wider range since he did a lot of ethnologist-related jobs (like record songs etc.) more than just your typical historian. He's also modern and like Scott, they are more critical of 'ealier' historians like Beyer so a lot of information they espouse I feel have a bit of correction and double thinking (in order not to repeat and mend inconsistencies)
One that covers a lot about practices (but not sure about pantheon since I've only read them as sources in other articles) I'm sure you would find interesting is the Bolinao Manuscript. I can't find it online but maybe if you search in your universities library you may get something. It deals a lot with the practices of the people of Pangasinan, although written by the sound of it relating to Kapampangan terms (so either they lump them together, or they were talking about the culture that existed in the area in general, that NW Central Luzonians shared) about practices of shamans and animistic priestesses.
On topic, last article Dr. Ambrosio wrote on the Inquirer about Filipino folk astronomy. It's about the eclipse and the native (and borrowed) culture relating to it in the Philippines.
ECLIPSE AND THE SNAKE IN THE SKY
Bakunawa and Laho
"The same attribution could be traced back through the past centuries. Fr. Francisco de San Antonio in his Tagalog vocabulary of 1620 said, "Linamon pala ng laho ang bouan kaya nangamarilim." (My trans not the article's: "Laho swallowed the moon that's why it there is only darkness.")
Fr. Tomas Ortiz, who died in 1742, reported that the Tagalogs would say, 'Linamon laho bouan' when there was a lunar eclipse. It was also written in the Tagalog vocabulary compiled by Fr. Juan de Noceda and Pedro de Sanlucar and republished in 1860 that they said, 'Quinain nang laho ang buan: linamon mandin nang laho.'
One of the Hindu-Buddhist elements that entered the Malay world long, long ago is laho. Aside from the Tagalogs, the Tausugs of Sulu and the Samas of Tawi-tawi call an eclipse lahu and the Pampangos, lauo. The Bataks of Sumatra see läu as the cause of an eclipse though they have quite a different story for this. The solar eclipses that occurred in Asia in 1988 and 1995 were said to have been caused by rahu eating the sun
But what is laho or rahu? In one version of an Indian myth, Rahu is a demon who chases after the sun and the moon intent on swallowing them. It was the sun and the moon which frustrated Rahu's attempt at immortality. Vishnu cut off its head and two arms after learning from the sun and the moon that it drank the potion that makes one immortal. Since the drinking was not completed, only the body died while the head and the tail became immortal. Since then, it has chased the sun and the moon to take revenge. When Rahu catches either one, an eclipse occurs.
But there is another snake that swallows the sun or the moon during an eclipse. To the ancient Bisayas, according to Fr. Alonso de Mentrida in 1637, the large animal that swallowed the sun and the moon was Bacunaua. This was the 'serpent that swallows the moon', binacunauahan ang bulan.'
As with laho, so it was with bakunawa: the attribution continued through time. To Fr. Ignacio Alcina who wrote in 1668, the Bisayas called the eclipse of the sun and the moon bacunawa because a big snake by this name swallowed the moon. In Fr. Juan Felix de Encarnacion's Cebuano dictionary of 1885, the eclipse of the sun and moon was called bakunawa. In his 1935 Bisaya dictionary, John Kaufmann defined bakunawa as a serpent or dragon that eats the moon and is exactly the term for the eclipse of the sun and the moon."
If you read the rest of the article, he talked in great details the rituals, superstitions and the folk beliefs that many Filipino still practice when there is an eclipse.
The Christian Science Monitor wrote about it (link is an article published in 1988) and it's quiet interesting how many of these beliefs prevail.
"Told by outsiders of the coming event, they stored extra food and water. During the eclipse, they hid babies indoors, locked up chickens, and struck brass gongs. People feared most that snakes might enter their bamboo huts.
All through the night before the eclipse, an elderly storyteller, Siboy Jenana, sang parts of a long and sacred T'boli epic about mythical hero, Todbulol, as many listened with tearful eyes.
Mr. Siboy told in a commanding voice how Todbulol prevented his sister from using an eclipse to destroy the earth after she saw the people living in misery.
``The eclipse is a test by the creator,'' Siboy said after the event, ``to show us that all this land, everything we see here, is not ours. This belongs to him,'' Siboy added. ``If he wants to turn everything upside down, we'll leave it to him.''
Another legend, says Manudal Maguwan, a T'boli shaman, says an eclipse occurs when a serpent swallows the sun. It ends, however, if the people play musical instruments to attract a monkey, who kills the serpent and releases the sun from its belly. That drama was acted out by the T'bolis just after the March 18 eclipse.
While such T'boli legends are being kept alive today, they are also being overshadowed by creeping Westernization: modern music, radio, and television. These have been introduced by the larger nontribal population of lowland Filipinos who have migrated into T'boli lands on the big southern island of Mindanao.
This trend, certain as the moon blotting out the sun, could signal twilight for T'boli culture.
``We believe our myths, but we have gone to school and learned modern science,'' says Peter Carado, a T'boli educator who has elected to work with his own people, designing curricula that includes tribal culture. ``We learned that the moon blocks the sun. But the old people still do not know this. We are in a transition period.''
The T'bolis, known for their distinctive abaca, or hemp, weaving and the heavy brass ``girdles'' laden with bells that the women wear, are one of 20 or so tribal groups in the Philippines."