Both the blood wizard decks I've tried have been mellow, especially for BBS.
BBS decks tend to be fairly steep, even though baker calls their concave mellow I'd personally say it's more of a medium, so trying some new wood might work better for you. DOA does some of their boards on the south central E mold which they call their "flat as fuck" decks. Highly recommend it if you want more of a traditional popsicle shape.
PS does some really great mellow decks...
- Quasi in general tend to be quite mellow.
- Toy Machine monster decks are usually on a nice mellow mold, my only gripe is that they're 14.5" wb.
- Some WKND decks have a mellow tail, the nose is almost always steep as fuck though.
- New Scumco Kyle Nicholson deck is one of the flat test and mellowest decks I own. I haven't skated it because it's 14.4" wb but I've heard that it's great (like all the broadcast series)
- New Scumco Brian Downey is flat and has a mellow tail, but the nose is more of a medium. I have skated that one and really liked it.
Sour has some pretty mellow shapes too but I'm not sure which one uses what. I think if you're a fan of bbs you'd like Jart wood, it's similarly stiff although the one I have feels a little thicker and heavier.
You can also search by concave on tactics but I don't know how accurate it is. I'm probably forgetting some but these are what came to mind. If you want pictures or more detailed measurements on any of these shoot me a PM.