@Rockho sorry I got lazy so I decided not to rebuild the Rahkshi combiner with the spear pieces 
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@DuplexBeGreat sorry to hear about your disappointment with Trinuma, I’m not even going to bother building it (risking to break the pieces).
Anyway, here’s Sentrakh:
I absolutely love this evil creature! It’s a very well built combiner.
This trusted dark hunter has a very interesting appearance. It almost seems like some kind of humanoid vulture. In fact, the head has some kind of beak more than a mouth, and the extra arms almost seem like underdeveloped wings.
It also has a strange moving contraption (mostly consisting of a Bohrok faceplate) that I imagine could act like some kind of deflector shield for Rhotuka spinners. If someone knows if in the Bionicle canon there’s an explanation for what it is, please let me know.
There are a couple of useless blue pins sticking out of the sides for absolutely no reason, but other than that, very solid model. If you have Sidorak and Keetongu, I definitely recommend building it.