Oric is after something. What do we know of that he could want?
A power sought out by evil rulers and corrupt dictators for millenea. One time-wrought eye gives life, another takes it. Total control. Total domination. Total and complete power.OVERSOUL.The reasons he could want this are manifold and, for the most part, obvious. Power.
So, why can't he just use this power himself? Well, we know what causes OVERSOUL:
Your Soul Guage is pushed to its current maximum capacity. Oversoul Mode activated.A soul reaching it's maximum capacity for charge.
We know that some soul stars charge faster than others:
And we also know that soul stars (can) have different soul charge limits:
Ciro's Soul Guage max capacity is now doubled. It naturally follows that Oric's soul star either charges very slowly, has a stupidly large capacity, or both, making it extremely hard for him to access Oversoul himself. This is (kind of) supported by the fact that the influx's max capacity was increased as an upgrade. it follows that power=capacity;
we know Oric has a very powerful soul star. (yes, I know this one's a bit shaky)
An alternate view could be that Oric's soul star has an exceptionally low capacity, either reducing the amount of power and control he gets with oversoul (and the length of time it lasts), or maybe even being too small to set off oversoul mode at all - hence requiring him to use his cohorts as batteries. (see Oric's Hammer, linked above).
So where does the Target fit in? Well, we know the Astral Influx charges pretty fast; we experienced an oversoul pretty early on in the cycle. My belief is that Oric wants to take advantage of this (potential) power, and this is apparently best achieved by having his siblings divert their efforts towards killing them.
(A previous theorycraft of mine touches upon this)