I think this is simpler than we think. Forced Movement doesn't provoke Atack of Oportunity (like Shift and Teleportation) ergo. when power says "if enemy move closer to you, you get Opportunity Attack" they won't get it with this kinds of movement. But if power says if enemy moves closer to you he get's another [W] + x damage then this powers don't prevent this. See Dire Radiance, warlock at-will attack power. There's already said if enemy moves on his next turn... So forced movement won't trigger extra damage if this won't happen in that enemy turn. The only option it could happen is readied action of an ally of warlock to use power with forced movement.
Also there shouldn't be any saves or knock you prone. Knocking prone is way to good and probably much better than damage in some situations. CS already said that forced movement into the power created terrain etc. don't have save or knock prone. So you can move enemies into Blade Barrier etc. without eny penalties.
And the last one. In 4E battles can be very long. I'm playing on 15lvl now and I realy thik that letting players such a combos is good. It's just make game little faster. Fighting solo for almost 2 houers isn't fun.
Also there shouldn't be any saves or knock you prone. Knocking prone is way to good and probably much better than damage in some situations. CS already said that forced movement into the power created terrain etc. don't have save or knock prone. So you can move enemies into Blade Barrier etc. without eny penalties.
And the last one. In 4E battles can be very long. I'm playing on 15lvl now and I realy thik that letting players such a combos is good. It's just make game little faster. Fighting solo for almost 2 houers isn't fun.