Through The Looking Glass may be used once by a player or given to any opponent to increase (Odd rolls), or decrease (Even rolls) their Cabbage or Water supplies by the amounts rolled.
For example, if a player rolls a 4 on the Green 12-sided die, and rolls a 7 on the Blue 12-sided die, then he will lose 4 Cabbage Units and gain 7 Water Units.
If a player gains Cabbage Units or Water Units by rolling an Odd number, then he must take them from the Discard Piles for those supplies. If the correct amounts of Cabbage Units and Water Units do not exist in the Discard Piles, then a player may either take Vouchers or keep track of what the game owes him. The player may take the supplies later when they become available in the Discard Piles.
If a player pays Cabbage Units and Water Units by rolling an Even number, then he must discard the amounts to the Discard Piles. If a player does not have enough (or any) of a supply, then he discards what he can. The player never owes the game any supplies after the card is played.