Is there any canon instance where Princess Diana of Themyscira (aka Wonder Woman)'s "Lasso of Truth" has ever snapped? Or is it truly indestructible?
The concept of continuity has become increasingly fluid of late with Grant Morrison's Multiversity which deems Earth-10 as, likely, to be the setting of Mark Millar's "Red Son", wherein Wonder Woman is subdued with her own lasso by Batman to serve as bait for the Soviet Superman. Wonder Woman breaks her bonds (and accordingly causes a shock to her own nature) proving the lasso to not be indestructible... but at considerable cost... only a shell of herself henceforth.
Incidentally, if enchanted to its limits, the lasso may be very hard to break indeed!
JLA Vol 1. #75