Can an opponent play a reaction during my turn when I play a unit with no triggers (Wizened Elder) and then buff it with Lee Sin's legend ability?

Ruling: The opponent can react to Lee Sin's activated ability, but cannot react to playing Wizened Elder since it has no triggers.

Sequence:

• Wizened Elder is played (no reaction window since no triggers)
• Lee Sin's legend ability is activated (opponent can react to this)
• Turn is passed

Nuances:

• Activated abilities create reaction windows for opponents
• Simply playing a unit without triggers does not create a reaction window