Jinnie Fay breaks those 1/1s wide open by making 2/2s and 3/1s to build a force that outscales the amount of mana you put into your spells
Whats really easy to miss, however, is that Haliya, Guided by Light also gains life when artifacts enter play under your control
That said, it has synergies here and there with loot effects or effects that require you to discard a card to play, so its a nice role-player in a discard-heavy strategy
The decks face Commander, Rootha, Mastering the Moment exemplifies this, as the bigger spells you cast, the bigger Elementals you make
No creatures will untap between the first additional combat and the second additional combat (or between the second and third, and so on, and wow, how long was Zariel under your control?!)