Actually, you can take any bloodmarked fighter as long as he have a right runemark. As all starblood stalkers have a seraphon runemark, you can take any of them as part of your warband. If you take a leader from an underword band as an ally, then you can include others members ot that band to your roster. Good way to make thematically interesting bands - ad kharadrons to dispossessed warband, mix daughter of khaine with dark elfes, add some chaos warriors to your demons of khorne etc. Nevertheless, the question is - are new warriors worth taking? So, from the beginning:
Kixi-Taka - the priest - is surprisingly good. Have profile of a starpriest, yet is 40 points cheaper. Cannot use tide of serpens, but have acces to new ability- on triple you can incerase speed and toughness of friendly fighters within 9'' by 1. Great on skinks, great on saurus, great overal. If you would like to have some support, don't look further.
Klaq-Trok - the oldblood - is ok. Slightly better than generic version, but only for 5 poins more you could have a sunblood with one more damage on crit and with acces to cold-blooded commander. If you need a heavy hitter, i would recommend the second one, or a guardian alpha. Yet, if you don't have points/ leader slots to spare, he is a viable option. And allows us to to have three tanky, heavy-hitting sauruses on field, if you would like to try ironjaws style of play.
otapatl - chameleon - is interesting option. With 1/5 blowpipe profile he hits slightly harder than normal skink, yet sucks in close cobat. Generally, you don't want to have a skink in close cobat, so it won't make much of a difference, and he still have acces to nimble retreat. What makes him actually useful is his new ability - chameleon ambush. On a double, with no visible enemy fighters within 12'', he can make an additional move. That makes him great for grabbing treasures and capturing an objective. For 80 points you get a unit which can move 18'' during one activation. Not bad, especially if you don't have points to spend on flyers.
Tok, Huachi end Xepic - guys with blowpipe, javelin and club. For 5 poins more than normal version, you recive 2 wounds more. If you have a 5 point to spare, you may took one, otherwise, don't bother. And DO NOT take a javelin version - it's still a trash.
What is actually important in this book, is a point change. Blowpipe skinks went up to 75 points, yet most of our heroes recived a slight discount. A much as i would like to see only discounts in seraphon section, I must agree with most of this changes. Althou I have no idea why slaan went up - he was little to slow and exepensive to begin with (yes, i know that few posts earlier i was prasing him), so this change will make him much harder to fit into a roster. But lorewise he never should have been availible, so...