How the price adds up
Everything a card does is worth points, and each point costs half an ember.
Cost at each tier
This card is so cheap that no tier would lower its price, so it can't be upgraded. It always costs 1.
Other Petra cards
Yak of the Frost-Line
Yearling of the Herd
Bearer of the World
Bison of the Stone Plain
Boulder-Sleeper
Bull of the Quarry Floor
See all 36 on the Petra page.