In the telling most often heard in the valley, Ghantakarna is not killed by a god or a hero. He is killed by a frog.
The versions vary in their details — in some he is lured onto ground that will not hold him, in some he goes after the frogs himself and jumps in after them — but the shape is constant: he ends up stuck in a marsh, unable to get out, and the villagers finish what the frog started, dragging the body to the river to burn it.
That a frog is the agent is worth noticing rather than skipping past. This is a monsoon festival, held when the paddy is flooded and the valley is loud with frogs at night, and the animal that beats the demon is the one whose season it is. The thing that saves the valley is the water and what lives in it.
It is also, transparently, a story that flatters nobody. The demon is not defeated by strength. He is defeated by being stupid in a swamp.
Related Places & Sites

destination
BungamatiPaddy country on the valley's southern edge, loud with frogs through the monsoon the festival falls in
Related
Connected places and entries worth pairing

Gunla
Gunla, the Newar Buddhist holy month, begins two days after the demon is burned

Gai Jatra
Charhe opens the festival season that runs on through Sa Paru

Sithi Nakha
The valley's other Newar cleaning festival — water sources in Jestha, houses in Shrawan

Bhaktapur Durbar Square
Bhaktapur's toles build the tallest and most competitive effigies

Thimi
Thimi and neighbouring Bode keep the night vividly

Banepa
A Newar bazaar town on the old Tibet road — the effigies go up here too

Panauti
Observed in Panauti's toles, on a smaller scale than the Valley's

Bandipur
A Newar trading settlement far west of the Valley that kept the festival

Tansen (Palpa)
Palpa's Newar bazaar raises its own effigies on the same night

Nag Panchami
Nag Panchami follows about a week later in the monsoon run of Newar and Hindu observances
Characters
Part of Gathamuga: Charhe