i did the math once for 20x10 dice rolls, i got back on average 220 coupons worth of items and a lucky pack

so dice r worth the investment but not by much key event gives a much bigger investment for your coupons since u get up to 40% off on some items and u know u get items u need, i dont need the coins cultivation runes or meat* now so those rolls are wasted.

if u cant get a full ninja during 1 event i would not spend coupons on it, because if u do and get it for free during a daily draw or it comes out in plot or something u may regret getting those few frags, or if a better ninja comes out for cheaper and u used the coupons then u miss the better ninja u could have gotten all frags for


thats not to say this event is bad, its definitely worth spending on if u have the resources since spending ingots gets u shuriken for the colorful balloons event too which means 2 ninjas for the price of 1, but in ur situation i would save, use the free dice for rune packs