One is a reapplying a theoretical concept observed while witnessing the effects of a spell, and translating that principal to Ulgu, which was noted to be sufficiently universal to be workable with all 8 winds. The other is trying to use a wind thematically tied with illusions to animate the the dead whereas even the wind associated with death runs into power uses compared to what necromancy can achieve.
It was penned by a mad genius using various translations of the Book of Nagash who himself was an asshole so I'd expect hidden rolls to determining whether, or not the simple act of reading the Liber Mortis adversely influenced Mathilde. Like I'm not saying something bad is guaranteed to occur, but expecting it to be like reading a normal magical tome seems like it would be an unwise presumption.
That seems like it would be trying to perform Shyish spells with Ulgu imo. Like if we want spells to be made using the principals of a cold hearted individual who was obsessed with avoiding death give it to the Patriarch of the Amethyst Order.
