Hmm, as a GM I have ran into this very problem lately, where one of my players (full cleric) decided to throw a Blood Crow Strike.
What strikes me about the spell description is that first of all the target of the spell is a single creature. And I believe that this is the target as revered to in the description. So the caster chooses a single target that is "marked" as the target of the blood crows (magical projectiles). And spell resistance applies once in order to prevent being marked. So you (the caster) cannot cast this on your allies (unless you want to attack them). Then for god knows how long (because the duration is instantaneous, which is really the weird part) you can make unarmed/flurry attacks against this marked target as if it was in threat range. Then it is very clear that when you deal damage with such an attack, the damage is half negative, half fire.
The description says nothing about allowing extra attacks either during casting or after the spell completes (after 1 round).
So as I read it, it is a 1 round action spent to gain the option of doing attacks at range (although it is a melee attack, see threat range) and changing the damage type. So all in all, not a great lvl 4 spell probably, but one that definitely needs some clarification.