Poll
7%
86%
7%
Ah, in Isard's Revenge, a book from the X-Wing series, Rogue Squadron makes short work of a quartet of Imperial Walkers with a pair of proton torpedoes apiece.
Seen as how Slave One's seismic charges, as its name implies, is made for ground attacks, it's quite clear that an AT-AT would get raped by the Slave I.