Once you do its hard to remove and even harder to kill in combat, and it can give you a winning boardstate in a single swing
Arch of Orazca seems like the most profitable way to gain advantage by having a lot of extra mana, but I could see playing a couple of small packages that combo well with Hour of Promise that allow you to do other things

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It used Gran-Gran and Artist's Talent to reduce the cost of spells and discard cards, Monument to Endurance to deal damage to opponents and draw additional cards as cards got discarded, and a variety of Lessons for their interactions and card draw
1 Reanimate At half the cost and some life for all of the reward, Reanimate is the best reanimation card in all of Magic's history and properly so
The card is a star in green Commander decks, and MTG Dinosaur players are particular fans, since this battle flips into a gigantic dinosaur creature which can really help you push damage through