Not quite thread necromancy but I once asked about protecting a horse from dying of shock at the end of "Steed of Vengeance" spell.
If a magus' Familiar was also their steed, and they wanted to enchant the Familiar Bond with a "Steed of Vengeance" effect, what needs to be done to keep the Familiar alive?
(would the Bronze Cord score help?)
Also, if the Familiar is a Hippogriff rather than a Horse?
Yes, certainly.
Invent a version of the spell where the steed does not die.
What is required to prevent the dying of shock possibility when the effect stops?
Adding a magnitude would be sufficient in my saga.
as I see it the stamina roll for the horse to survive could be seen in one of two ways- shock because the poor animal had no idea what was coming, in which case familiars would be immune, or it was a result of a glitch in lab experimentation, since there is nothing else in spell development that would result in this kind of effect. So simply re-inventing the spell without lab text or experimentation should suffice.
I see the Stamina roll as a minor flaw built into the spell due to experimentation. So I concur with silveroak on that.