Thank you for checking it out!
Each class has a Power Pool of 1, and always has at least 1 die. They each have abilities that can add dice to the pool. The GM can subtract 2 dice if an action is risky, but you will always have at least 1.
The Reapers Mind Pool is a little different. You have a pool of points, and can add them when using psychic powers. When you do, any 1's you roll leave your Power Pool until you next regain HP.
Only the Reaper has a Mind Pool.
If the GM subtracts -2 from your roll, you put those Psychic Dice back into your reserve pool, you don't lose or roll those ones.
I hope this makes things more clear. Let me know if you have any more questions!