Tiny's Trial is a crafting station minigame found in Betrayal league safehouses when Guff is one of the members of that division.
Players have a limited time to apply various currencies to one of their items. The currencies are somewhat random but include high-level items such as Lua error: Error: invalid field alias "items._pageName"; aliases cannot contain dots or quotes.. and Lua error: Error: invalid field alias "items._pageName"; aliases cannot contain dots or quotes... The currencies are provided by the game and are not taken from the player's inventory or stash.
The experience can be simulated at https://poesimulator.github.io/trial/. In this simulation, players left-click to apply currencies, rather than picking items up with the left mouse button and applying them with the right, as they do in the real Tiny's Trial.