If the source of a triggered ability is removed from the board (e.g., using Gust on Solari Shieldbearer in response to its Play trigger), does the triggered ability still resolve?

Ruling: Once a triggered ability has been put on the chain after its trigger condition is fulfilled, it will resolve even if its source is removed from the board. Removing the source does not prevent the ability from resolving.

Sequence:

• The trigger condition must be fulfilled while the source is in the appropriate zone (on the board for permanents)
• Once the condition is fulfilled, the triggered ability is put on the chain
• After the ability is on the chain, removing the source does not prevent it from resolving
• The ability resolves to the fullest legal extent possible

Nuances:

• The source must be in the appropriate zone when the trigger condition is fulfilled for the ability to trigger in the first place (e.g., Darius in the trash will not trigger when you cast your second spell)
• If a unit dies without death knell, its "when a unit dies" triggers don't see its own death because it's no longer on the board when the trigger condition occurs
• Delayed abilities are unique in that they exist independently of their source and can trigger even after the source has left the board, but once any ability (triggered, delayed, or reflexive) is on the chain, it resolves regardless of the source's location