I've never seen these scrolls before. However, one day I had a stall up trying to sell a lvl 4 challenge stone. A player came in and offered to trade a monster scroll for my stone. I turned him down because the way he was talking, he was just trying to scam me. Basically he told me to use the scroll out away from town where there are no other players, kill the summoned monster and I'll get a "ton of money"
I wasn't buying his story at all, but that's the first I even heard of a monster scroll.
Missing the good times in SRO...
SRO: 1x, STR Blader (Thebes) 54, STR blader (Venice) 0x, INT wizard (Venice) 19, INT spear (Venice) 34, STR rogue/bard (Venus) 0x, STR blader (Venus) 8x, INT bard/cleric (Gaia)