Does using Kai'sa Evolutionary's conquer ability to play a spell from your discard for free trigger Lux's legend ability to draw a card if the card's cost is 5 or more?

Ruling: Yes, playing a spell for free with Kai'sa Evolutionary's conquer ability will trigger Lux's legend ability if the spell's base cost is 5 or more.

Nuances:

• The ability checks the base cost of the spell, not the actual amount spent to cast it