The VOIDRUNNER'S CODEX is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
Re-read the Familar rules. They all have Improved Evasion (half damage from area attacks on a failed save, no damage at all on a sucessful one) for this specific reason. Unless the Wizard will die fom one failed save the Familiar sure won't.
So, to answer, they keep them alive by following the...