Seven players, round two. P3 said "Dapp!", P4 passed, and you are P5.
Your hand
Do you call "Challenge!"?
Answer
Call “Challenge!”. The XXI with one other Tarok is a trump stop, so this is a hand you would claim yourself, even with only two Taroks. If the bidder says “Go ahead”, you rebuild around the XXI; if they keep the Dapp, you defend a hand that pays double.
Rule: Call Challenge with a hand you would claim yourself, a trump stop on the ladder, and pass without one. The bidder chooses whether you play it, and either way the hand pays double.