I cant decide between Trans Magic and the power to be able to infinitely summon a device at no cost any time that will answer correctly and precisely any question i ask it for no price, it knowing what i mean and wanting to help me. Summoning it will erase the previous device, keeping the memory of the information obtained from it
They don't need to understand it, they just need to ask it a question that refers to it and some surrounding algorithmic structure to create the paradox.
A well prepared mathematician, skeptical of the functioning of the oracle devices could speak that question in a few minutes.