Seven players. P4 is the Dapper and laid the Pagat face-up as a Pagat Ultimo; P5 called "Challenge!". You are P7 and won trick 4, so you lead trick 5 of 6.
P2Team
P3Team
P4Dapper
P5Team
Challenge!
P1Team
P6Team
P4's declared Pagat Ultimo (face up)

Your hand


Pad
- Already played: the Skus.
Which lead makes sure the Pagat Ultimo fails?
Answer
The Q
. Keep the XIV for the last trick: whatever is led there, it is your only card, and it beats the Pagat. If the Dapper has no Heart and no other Tarok, he must play the Pagat now, and the Ultimo fails at once. Lead the XIV and a Dapper who still holds another Tarok plays it, keeps the Pagat, and wins the last trick with it if nobody on the team has a Tarok left.
Rule: A declared Ultimo card stays visible and may not be played before its promised trick unless no legal card remains.