What is the difference between casting lots and playing with dice, and is it permissible to play cards after changing some of the rules?

Casting lots is not gambling, nor is it a forbidden form of divination (istiqsam); because it is for distinguishing rights, removing ambiguity, and resolving disputes. It is permissible in this context. As for casting lots intended for seeking good omens or knowing the unseen, that is a forbidden form of divination. Games based on luck and speculation are prohibited by analogy with dice, even if the playing instrument changes, because they resemble it in relying on speculation, which leads to foolishness.