Obosh-based decks have been doing exceptionally well last year due to the double damage of their creatures. But Calamity Bearer is 1 Mana cheaper and basically works in the similar fashion as Obosh, the Preypiercer.
Kaldheim offers a huge support to the Giants tribal decks and players should exploit all of it. You will see all kinds of Giants decks this season, including Mono-Red Giants, Jeskai Giants, Temur Giants, Naya Giants, and all of them will play Calamity Bearer.
The card itself is actually a 6/4 Giant for 4 Mana and not a 3/4. Plus it has a huge upside, which definitely makes it a tribal winner of the Kaldheim set.