Actually this does bring up an interesting idea - premium dungeons. What if we had a secondary "mist" bar like the olden days that can only be used for the premium dungeons? It would work beautifully for events as a replacement or extension of the prestige missions, and can easily rotate even more!
This means people who wish to farm the event can dig into their energy reserves if they love going into it. A premium pass for unlimited action could be sold for $15-$20 and last for the duration of the event.
The base game needs to retain its free elevators. Making events be a timed investment or something you can farm, then go farm for crowns and trade for energy to keep doing the event means you can always be working towards the event without ever feeling pressured by not playing during an event period. This brings back a reason to even have energy, as right now it's just "premium currency", which is understandable but boring.
Lore-wise, explain that when these events happen energy surges are sparking throughout the clockworks, powering down these specific elevators and instead sending the power into the air.
I mean, even if you did not pay for the energy you own, someone somewhere paid cash for it. I don't think that there has been any instance outside mist energy where the game has given out free energy to players, unused mist tanks were converted into sparks of life, so can't you just use energy to pay?