The original Ketria Triome appeared in Ikoria: Lair of Behemoths Promos, in 2020.
The original art was by Sam Burley.
The List
Ikoria: Lair of Behemoths Promos
Ikoria: Lair of Behemoths
Ikoria: Lair of Behemoths Promos
Ikoria: Lair of Behemoths