How many times does Leona's leader skill trigger when stunning units, and does it matter if multiple stuns happen on the same chain or from the same effect?

Ruling: Leona's leader skill triggers once per effect that stuns one or more units. Multiple stuns caused by a single resolving effect only trigger Leona once, but separate effects that each stun (even on the same chain) trigger Leona separately.

Sequence:

• If one effect stuns multiple units simultaneously, that counts as "1 or more" and adds one trigger
• If separate effects each stun units (even on the same chain), each effect triggers Leona separately
• Effects with "do this twice" create separate triggers on the chain that resolve individually, so each iteration triggers Leona
• Triggers are added to the chain after the effect that causes them completes

Nuances:

• An "effect" is something that is added to the chain to resolve
• Targets for "do this" effects aren't declared until each trigger hits the chain, so targets can change if original targets become invalid
• If valid enemy targets are gone when a stun effect resolves, you must stun your own units if required
• A hypothetical "stun a unit, then stun another unit" on a single effect would likely only trigger Leona once, though the rules are somewhat unclear on this edge case