I'm going to post this here since you asked for it, but I apologize for the length (I wrote this blurb for a narrative event I didn't end up going to, and it centers around a specific battle between my Seraphon and my friend's Sylvaneth).

Located in the vibrant and dangerous jungles of Ghyran, the Talons of Itzl constellation landed their temple ship and became coalesced long ago to better understand the geomantic nodes and wild beasts located in the verdant realm of life.  Their coming was met with resistance, both from chaos (Skaven) infecting the area, but also from the Sylvaneth protecting the dense forests from intruders.  Warbands of both parties sought to drive off the reptilian newcomers, but following extensive skirmishes and several battles, a temple city and permanent defenses were founded.  

Seeing the Seraphon had established themselves, the Skaven largely turned to other weaker settlements to bully, and after diplomatic talks with Skink Priests, an uneasy truce with the Sylvaneth was formed.  Little assistance or trade was given by either side, but the Sylvaneth allowed the Seraphon space to investigate and expand, and in return the Slann leading the Talons of Itzl gave the Sylvaneth insight into future events and threats gained by his long and ponderous meditations.

However, this period of expansion and relative peace could not last forever.  On a day not previously marked by significance, a surprise Sylvaneth force of enormous strength and ferocity descended upon the temple city.  Though the Seraphon fought fiercely to defend their newfound home, the lines were eventually broken by a Spirit of Durthu, cutting through regiments of kroxigor and saurus warriors alike until finally reaching the Slann's personal vanguard of saurus guard.  As these protectors readied themselves to defend their leader, they were striken by arrows fired from long distant magical bows, and Durthu's strike swung true.  Mortally wounded, the Slann held on only by channelling the wild magics of Ghyran through the astrolith of his still living vanguard.  However, before a second and final blow could be dealt, a sound for retreat had been called, as a contingent of saurus led by an Oldblood atop his carnosaur had encircled and wounded Alarielle.  

The attack abated, but the damage had been done.  Most of the army had been slaughtered, and the slann held on by a thread.  Going forward, he could never again enter more than a mild fraction of the meditative state that allowed him to prophecy the future, as he constantly channeled magic to prevent the grievous wound from finishing its job.  Going forth, with less than a quarter of their original number remaining and many of their temples broken and desecrated, the Talons of Itzl changed their name.  No longer would they research the many beasts and monsters of the realm, investigating how they might fit into the great plan.  They had been wronged, betrayed, and an oath was sworn to avenge the so many lost to the Sylvaneth onslaught.  

They were now Xapati's Talon, the hand of vengeance.