When using "blood magic" on a character that had ~138hp, they *gained* 11 health and 5 mana. (lost negative 11 health), and again at 149 health, they lost -12hp and restored 4mp, bringing me to 161 hp.
I'd assume a 1 for 1 exchange for health and mana, and it looks like the ""10%"" referred in the tooltip is talking about mana? as they are now at 52 mana.
Blood explosion was also weird and a disappointment. I had pictured my character exploding in gore to hurt all enemies, but instead it does massive damage to a single enemy and then doing damage to everyone else. In the test I just did, the target took 132 damage, and everyone else took 31, which is about 23%. ..the target has 150 total health, so is the 20% from that rounded up?
The tool tip implies **you** explode, that the caster takes health damage to cast the spell.

Considering the relatively high requirements and the high mana cost, I expected the class to pack more punch.

if nothing else, I wanted to bring the sign error to your attention