again with the palm slicing!
from tvtropes:
When magic spells call for blood, where do you cut? Right across your palm, of course. Because there certainly aren’t any sensitive muscles or tendons there. Plus it heals super fast, and you rarely use your hand anyway, right? Especially in the upcoming boss battle.
The out-of-character reason for this trope is that it’s easier to stage blood seeping from a palm than, say, a fingertip: there’s more space to hide the tubing or packet for the fake blood, and it doesn’t need as tight a close-up for the audience to see what happens, so less-detailed latex appliances can be used to conceal the mechanics of the special effect


