The trick is keeping him alive long enough to hit everyone, as we can't pick who to attack at a given time, and to slip him past whatever defenses may come up
There were more strange subsections of this rule, but as even ordinary banding was kind of hard to understand a few years ago (and still is today), I wont go into to much details
Grumgully is nowhere near as good as the other two options and is only of middling use during the game
Cards like Kaalia of the Vast and Kaalia, Zenith Seeker fit perfectly into angel-focused decks and can even lead the deck as your commander
Wait, didnt we just do this two weeks ago with Modern Horizons
Avoid fights whenever possible, as your characters arent great at challenging, unless you use the Challenger and strength effects