The hero power is useful in the early game, because you can freeze the whole Tavern using the standard freeze instead of the hero power (even multiple times) and all minions will get the stats buff.
The hero power is also useful in the late game, because you can freeze a single good minion or spell and will still get a free refresh of all the other cards at the beginning of your turn.
The hero power is also useful in the late game, because you can freeze a single good minion or spell and will still get a free refresh of all the other cards at the beginning of your turn.