Perfect Critical

Select a Baseweapon for which you have already selected the "Improved Critical" feat. For Weapons of the same type, you deal critical damage even more often.
Both feats combined grant:

• When hitting with a roll of '19', roll another attack with same bonuses as the '19'-roll (this attack cannot be modified into advantage/disadvantage by any means). If it hits, roll the damage as if it was a critical hit. Otherwise, roll normal damage.
• When hitting with a roll of '18', roll another attack with same bonuses as the '18'-roll with disadvantage (this attack cannot be modified into non-advantage/advantage by any means). If it hits, roll the damage as if it was a critical hit. Otherwise, roll normal damage.
• When criting with a roll of natural '20', all damage rolls roll maximum damage.