Cerberus tranformation

Cerberus mode a mode where you use one action where you change human like Cerberus instead of having 3 head he gains hell armor which gives 3 to my ac to 2 to each bite
claw attack but cant use weapons or spells also my claw and bite gain burn 2d4 every turn you have roll a 15 higher for you not to take damage since you are at a lower level
if you roll lower then a 15 you roll a d6 for damage you do these until end of combat phase or until 5 hp also gains resistance to fire damage any fire damage is half
at level 10 you roll 1d4 for damage at level 15 you stop taking damage cause you have learn to control the form
if any fire attack is used in my area the damage is double
fire damage and the attack is half