Basically, you can pray for anything, but the bigger/rarer/harder-to-do it is the more prayer it will take. Also, your current basic talisman might not be able to support the amount prayer required for epic shit.

Also, for those team white people wanting to kill Nat, in normal circumstances the gods punish harshly for direct, intentional friendly fire, but Nat has already pissed off your god so you won't be punished for killing him.