Frozen Mallet Successfully Equipping to Volibear and Other Possible Bugs
Currently, it is a known mechanic in TFT where if you create or add a class buff item (BORK, Yuumi, Frozen Mallet, Knights Vow, Youmuus & Darkin) to a champion with that class already, it should un-apply from the champion and go back to you're inventory.
After 3 tests in the last 2 weeks, I am certain that currently when creating or adding a frozen mallet to Volibear it will successfully equip, not unequip, effectively making the very powerful item useless unless you sell the Volibear.
I suspect multiple other champions have this bug and it really should be looked into, specifically frozen mallet and glacier champs.