Channel lets you pay life to generate a huge burst of mana, and then Fireball turns that mana into lethal damage in one shot
While changes to older, non-rotating formats are fairly common, the banning of cards in Standard is incredibly rare, and Wizards does its best to avoid them
You could build an aggressive deck that uses Bre as a card advantage engine to maintain pressure or go taller and focus on giving your biggest creatures lifelink and flying
Once you get to attack with it, it enables you to leverage your yard as a second hand
If the other creature is still a legal target, it's returned to its owner's hand
Not only are there are a whole slew of powerful rares and mythics, but were seeing cards that might normally be mythic pushed down to rare (like Shalai, Voice of Plenty) and rares pushed down to uncommon (like all of the non-Rona multicolor uncommon legendsjust look at all of that text on Garna!)