It's either a misdescription, or a misimplementation. As well as preventing damage, Toughness functioned as a block against a "push back" attack: not only was the damage cancelled, but also the slide effect.
Interesting. http://wiki.cardhuntria.com/wiki/Basic_Card_Mechanics might get a new entry. Are you sure you didn't have immovable when this happened? My own memories of push attacks used on me while having toughness are foggy.
It's a pretty easy one to recreate. Running any toughness card against Mom and running up to Bopsy should test it!
Yeah, sounds a lot like immovable to me. Was the target next to blocking terrain? Are you sure you know which way the game wanted to push the target? Maybe the direction where it tried to push was blocked? I'm asking because I use the spell sometimes from weird angles and I never really know where the target will go.
It's possible we both missed immovable, of course, but if anyone gets a chance to recreate, can they please confirm? It was a straightforward bash attack into open space.