Your FIRST ban should be Yi. He scales so fast in this mode that if he's open the game becomes Defend The Master Yi
Then ban according to the 1st game mode:
* If it's URF Deathmatch, ban veigar, unless you want him to stack like crazy during the event. And I mean reaching 150-200 stacks at 6
* If it's Bardle Royale, ban poppy, unless you fancy getting booted off the ring, lose the event, and risk the enemy team getting an easy sled or catapult.
* If it's not any of those 2 events or both bans are already locked in,idk , just ban whatever you usually ban in ranked, there's not any extreme cheese in prize fight or scuttle racing
OFC, there's one exception to the previous rules, don't ban them if someone in your team wants to abuse those champs (However odds are that they'll be banned by other team, especially yi)