Mesmerise is an advanced vampire power of mind control. It turns a normal enemy into a temporary ally, and you only get one chance to unlock it, through Lacra's story.
Target a non-boss enemy and it fights on your side for a while. It is strongest against big groups where one turned enemy can tie up the rest.
Play The Night of Horrors with Lacra. Most guides tie it to drinking her blood: in the romance scene, or from a vial she gives you if you skip the romance. PC Gamer credits eating the mandrake instead, which other guides say grants Mandrake Ward. To be safe, eat the mandrake and take the blood.
Night only.
It is handy, but there is only one source of Lacra's blood and it takes an ability slot. One guide advises against spending many skill points upgrading it.
Blood Surge
Makes a target explode through their own blood.
Claw Ride
A vampire traversal skill for moving around the rooftops at night.
Crimson Rush
Active powers deal more damage the healthier Coen is.
Image: Rebel Wolves / Bandai NamcoNourishing Blood
Drinking blood restores more health.