Your tumor familiar goes to any length to save your life.
Prerequisites: Tumor familiar alchemist discovery.
Benefit: If your tumor familiar is attached, and you would be reduced to 0 or fewer hit points by damage in combat (from a weapon or other blow, not a spell or special ability), the familiar throws itself in the way of the attack as an immediate action. If it makes a Reflex saving throw (DC = damage dealt), it takes all the damage from the attack; if it fails, it takes half damage and you take half damage.
The familiar must be aware of the attack and able to react to it in order to use this ability, and it can only do this once per day—if it is denied its Dexterity bonus to AC, it can’t use this ability. Since this effect would not normally allow the familiar to make a Reflex save for half damage, its improved evasion ability does not apply on this saving throw.