Does Evolutionary Kai'Sa's conquer ability allow you to immediately play a spell ignoring timing restrictions (e.g., casting a non-reaction speed spell in response to an enemy's Charm)?

Ruling: Yes, you can play any spell that Kai'Sa can legally select, and it goes onto the chain and resolves like normal. The speed of the spell she picks is not part of her targeting requirements.

Nuances:

• The ability allows you to cast spells regardless of their normal speed restrictions
• The spell still goes onto the chain and resolves following normal chain rules