Going by RAW, I agree with those pointing out forced movement is not affected by difficult terrain. If it's a matter of making a sensible narrative from that mechanic, I might describe the roper lifting the character bodily off the ground as part of its pull, more like a swift yank than being dragged. Generally speaking, we might assume every type of forced movement grants the target at least a tiny amount of clearance off the ground in order to apply the effect in the strictest technical fashion.
That said, I like Sorcerers Apprentice's take on it. I wouldn't begrudge any DM who pulled out a ruling like that if I were a player. As a DM, I might even take a RAF approach and increase the base amount of forced movement over slippery terrain like ice.
That said, I like Sorcerers Apprentice's take on it. I wouldn't begrudge any DM who pulled out a ruling like that if I were a player. As a DM, I might even take a RAF approach and increase the base amount of forced movement over slippery terrain like ice.