"ITD" hmm...yah, guess it is useful err....on pvp? maybe ? hahah, not really much do pvp xD
Still, i think -Def debuff is better coz that "ITD" only got effect on that skill alone with shortest CD 16s,21s,and 1m, so cant really depend on that 3 skills much in pve.
as for -Def Debuff, its applied on all our skills and party too, right? so yah, I want to help party too even its just a little, while using crus,haha.... and for "atck power" buff, i think most dps class got their own "attack buff" too.