Does Sett - Brawler trigger Fiora's leader ability when he spends his buff to get +4M, or when he is played?

Ruling: Yes, Sett triggers Fiora's leader ability both when played and when he spends his buff. He momentarily exists at 4M before his buff applies or reapplies.

Sequence:

• When played: Sett enters at 4M, then his triggered ability goes on the chain to gain the buff
• When spending buff: Sett goes to 4M, then his activated ability goes on the chain to gain +4M
• In both cases, there is a window where players can react while he is at 4M

Nuances:

• The ability goes on the chain, creating a real game state where Sett is at 4M for a considerable amount of time before resolving