Star Wars: Rogue One Trailer Breakdown - 34 Things You Need To See
9. Taking Down An AT-ACT
Here's Baze with his "big gun" (I'm getting Celebration spoiler flashbacks), which swiftly explains why he's on the team, but also leads to an amazing action beat.
He's shooting a rocket at an AT-ACT (a modified AT-AT), which is so beautifully David and Goliath and also reminds that legs aren't the only way to stop these beasts.
It's unclear if this moment is a quick bit of spectacle or a major character point, with Baze taking on the walker in a final stand, but given the ferocity oft he Scarif battle, I'm willing to say the latter.
While we take in that awesome shot, let me get technical; Rogue One provides some in-movie evidence of the correct pronunciation of AT-AT, These are All Terrain Armored Cargo Transport, abbreviated to AT-ACT, which only works on a pronunciation level as "atact". So it is "at at". Mystery solved.