Oh, so that's where it's from. I've seen it in the SSA data and assumed it was like a combination of
Ava and
Allison with a variant spelling. I'd pronounce it the same as you.
The popularity of it lines up with the release of the Magic card too:
https://www.behindthename.com/top/beyond.php?name=Avacyn
The sound isn't bad but -cyn looks medicinal to me. But Avasyn and Avasin don't look much better. Hm.
Maple Cassander Poet
Augusta Aubrey Silver
www.behindthename.com/pnl/59411