One interesting bit of information for all of us spellcasters out there is that they did away with familiars. Gaining the services of a familiar is now a 1st level ritual spell that only a wizard can cast called "find familiar." The abilities of the familiar are far less potent than that of 3.5 and limited to a handful of simple forms (bat, cat, crab, hawk, etc.). If it reaches 0 HP, it simply vanishes until you cast the ritual again, or you can temporarily dismiss it into a pocket dimension as an action and make it reappear as an action.