How does 4c Lux's ability work? Does she provide ramp or temporary energy, and do the resources stay after the turn?

Ruling: Lux does not provide ramp. When you exhaust her, you get 2 energy that can only be spent on spells during that turn.

Sequence:

• Exhaust Lux to gain 2 energy
• This energy can only be used for spells
• The energy does not persist beyond the current turn
• On a 6 rune turn, you can exhaust 6 runes + Lux to play an 8 cost spell

Nuances:

• This works similarly to Kai'Sa's Legend ability, though Kai'Sa gives Power instead of Energy