Floor 18 Secret Item - Kouchu Kabuto Condition - Stand on all corners of the stage. Floor 19 Secret Item - Longhua Qippo Condition - Switch with ally at least 5 times. Floor 20 Secret Item - Life Gem:Sun Condition - Clear the Stage with a Critical Finish. *Useful Skills - Soul Gauge Damage A, Double Edged Sword and Soul Gauge Vamp. *Useful Characters - Yun Seong, Voldo and Seong Mina. ... Soul Calibur IV tower lost souls floor 18 19 20 critical finish secret item chest treasure unlock ...