Can both aspects of Treasure Trove be reacted to - the 'Kill this' ability and the 'When this leaves the board' trigger?

Ruling: Yes, both aspects of Treasure Trove can be reacted to.

Sequence:

• The activated ability (Kill this) creates a chain to which Reactions can be played
• Once that ability resolves, the trigger from it leaving the board creates a new chain
• Reactions can be played to this second chain as well