I wanted a pair representing good and bad luck and found out that Tyche (goddess of fortune) had dice called the "Tykhai", for deciding fortunes. I gave them nicknames related to what kind of luck they bring.

I don't know how they work in the mythos, so here's my headcanon:

1) Roll their dice forms together (they don't work at a time). Higher number gets to use luck.

2) Ties allow for both of them to use their powers.

3) The power of luck (good or bad) lasts for 1 minute x the number landed.

4) They can only give luck via physical contact until the assigned time limit is up.

5) Each roll (including draws) drains stamina (10% x the number) from the thrower.

6) The numbers represent how much luck the recipient receives.