I have a question about Barrier, when used is it blocking terrain and can it be destroyed by your opponent. Also can you fly over it or phase through it for movement.

yes Yes, or by you yes, if it is outdoors yes.

So an opponent can fly through it and base you, What would be a good stratagey then in using barrier.

It's mostly used for blocking lines of fire, but it can be good for trapping or figures.

Excellent. Thank you for that answer!

Yes thank you, never thought about using it to trap opposing players. But can anyone destroy a barrier or do you need certain abilities? I I believe that would also be a power action to destroy the barrier.

Since Barrier markers a blocking terrain, they can be destroyed in the same way as regular blocking terrain - all you need to do is to deal 3 damage to it.

Destroying Blocking Terrain takes 3 damage, and (normally) requires an attack. The attack automatically succeeds.

A fun thing to do with Barrier is pair it with Outwit. Use Outwit to Counter someone's Flight, then surround them with 4 Barrier tokens. They're not going anywhere.

Works with Sentry and Void, too.

You can even do this with smoke cloud if you place the markers right. If they're not already in hindering, their first square of movement will bring them into hindering and force them to stop.

And people say smoke cloud isn't useful...

You can also barrier your force into an area where there are no open squares. Even if they can fly, they must land before they can attack. If you are completely enclosed you can not be attacked unless they take out the barrier first (or have line of fire to you another way).