When Amleth (Summer)’s skill is used in the Tower of Infinity, to what extent will its effect activate?

Regarding [A Midsummer Day’s Dream] Amleth’s Active Skill, “Lightning Flash,” the effect it has when used at Lv 2 or higher in the Tower of Infinity, where it decreases all targets’ P. DEF by 50%, will also activate in the Tower of Amber.