Fuse cards and Dream Halls
Sorry for the delay on some of these questions. Some of these questions involved a lot more discussion, and some just slipped through the cracks. We're going to play a little catch-up now.
All fuse cares about is that you're casting it from your hand. So yes, you can cast a card with fuse from your hand, then use Dream Hall's ability to discard a card that shares a color with the fused card to cast it.
Nathan Long
Magic Rules NetRep