Just got a question while reading about a tie up strategy using Barrier... question is this... Barrier 'squares' can be destroyed just like any blocking terrain/walls, correct? 3 damage and the square goes from blocking to hindering, right?

I'm wondering, what happens to the square of barrier when it gets destroyed, does it become hindering terrain or just disappear? And if it becomes hindering terrain, how long does that stick around?

It becomes hindering terrain and it goes away when the rest of the Barrier goes away.