The WTC followed by the Mansion Gauntlet has been my favourite part of Reborn for quite a while, just feels so catarthic and the double battles are fun and challenging.
Tbh, wtc is shitty cause of titania. Taka tries his best to make it bearable with him asking for a battle in the end but we all know how this decision affects later parts of the game . Mansion battles does indeed give you a great feeling though