@melott-
I saw that card on eBay, as well, and thought about tossing in a bid on it, but decided against it. Glad an Amiga.org'er got it. Kind of a rare item, I think.
MagicBox is a video company who resold A1200s and CD32s boxed as turnkey infochannel packages. The
Alphagen was a repackaged A1200, and this was an accelerator card for that machine.
My guess (and this is certainly a guess) is that it might be a re-branded DCE board. Check the A1200 accelerators by DCE that are listed on Amiga-Hardware, and see if any of those look like it.