How about add to game system of item duels?
Op command like that:
/itemduel [nameofplayer] [number] [nameofitem1] [nameofitem2]
Means player it types wants to duel his [nameofitem1] for [nameofplayer]'s [nameofitem2] first to [number].
Then [nameofplayer] recieves message and details of duel, and types
/acceptduel
Then both players' items work as tc in normal duels.