Hello there.
Battleground related: When Maiev’s ability resolves on divine shield minion, while Drakonid Enforcer is in Bob’s tavern – it will permanently become buffed for +2/+2.
Here’s a clumsy ss – postimg.cc/1nQy8nRW
UPD:
Same goes for frozen minions. If you freeze tavern tier, then imprison a minion – it will be frozen when you play it (albeit once battle begins it’ll unfreeze)