Can you tap Kaisa's legend ability to pay for Deflect's increased spell cost?

Ruling: Yes, you can tap Kaisa's legend ability to pay for Deflect's increased spell cost for regular spells. However, you cannot use it to pay Deflect for reflexive triggers (like Fallen Star's damage triggers) because reflexive triggers are abilities, not spells.

Nuances:

• Deflect increases the cost of spells, so Kaisa's legend ability can be used to pay that increased cost
• Reflexive triggers (such as Fallen Star's damage triggers after resolution) are abilities, not spells, so Deflect cannot be paid for them
• You can still use Kaisa's ability to react to reflexive triggers and play a different spell, but not to pay Deflect on the reflexive trigger itself