If Pit Rookie is played and its buff ability targets a unit, does bouncing the Pit Rookie with Gust prevent the buff from being applied?

Ruling: No, bouncing Pit Rookie with Gust does not prevent the buff. The buff still applies to the targeted unit because once the ability becomes a chain item, its source doesn't matter anymore.

Sequence:

• Pit Rookie is played
• Pit Rookie's when played buff ability goes on the chain and targets a unit
• Gust is played in response to bounce Pit Rookie
• Gust resolves, returning Pit Rookie to hand
• The buff ability still resolves and applies to the target

Nuances:

• You are responding to the unit's when played effect, so you will know the target of the buff before you can play Gust
• The ability resolves as long as it has a valid target, regardless of whether the source unit is still in play