Does Leona's stun ability still work if Leona is killed or removed from the battlefield during combat before the ability resolves?

Ruling: If Leona is removed in response to her ability triggering, the ability does not work because "here" is undefined when Leona no longer exists on the board. However, if a unit is already stunned and then Leona is removed afterward, the unit stays stunned until end of turn.

Sequence:

• Case A: Leona attacks and stuns a unit, then Leona gets removed - the unit stays stunned until end of turn
• Case B: Leona moves to battlefield and targets a unit with her ability, opponent kills Leona in response - the ability resolves but does nothing because "here" is not defined anymore

Nuances:

• Abilities do resolve even if their sources are removed, but if those abilities need to know anything about the source (its controller, Might, or location including "here"), they find a null value and don't work
• Moving Leona to another battlefield or to base also prevents the ability from working
• Yasuo works the same way - removing him in response to his trigger prevents the damage