Can you kill gear with 'Kill this:' text at any time, or do you need another card effect to kill it?

Ruling: 'Kill this' is a cost you can pay, not a discretionary action. You can activate these gear abilities on your turn prior to a chain and prior to a showdown by paying the cost of killing the gear.

Sequence:

• Must be activated on your turn
• Must be prior to a chain
• Must be prior to a showdown
• Pay the cost (kill the gear) to receive the reward

Nuances:

• 'Kill this' (an instruction/cost) is different from 'When I'm killed' (a condition that triggers when the gear is killed by other means)
• Paying costs is separate from discretionary actions