The Thaw
The Thaw, also known as a Flood Ages, is the era in Dominaria's history started from cast of World Spell. Only some areas of Terisiare (including Almaaz kingdom) were unaffected by great floods which destroyed vast parts of continent splitting it to few landmasses.
Shortly after the World Spell an individual named Heidar tried to halt and undo the Thaw with his Rimewind magic, but ultimately failed.