Re: Strengthen (Blood Rune Magic)
Hullo, Gilgamesh,
While I would have said that under normal circumstances the spell would have a Difficulty of 3, I gather that here it's a function of the fact that one is carving the rune into the body of the target of the spell that makes the Difficulty drop by 1. And I believe it would be 2 successes (which gives a basic success) for the +1 bonus to Strength.
Just my $0.02, of course.