Whenever you activate an ability of an artifact or creature that isn't a mana ability, Crackdown Construct gets +1/+1 until end of turn.
2/9/2017 Activated abilities are written in the form “Cost: Effect.” Some keyword abilities, such as equip and crew, are activated abilities and will have colons in their reminder texts.
2/9/2017 An activated mana ability is one that adds mana to a player’s mana pool as it resolves, doesn’t have a target, and isn’t a loyalty ability.
2/9/2017 Crackdown Construct’s ability doesn’t trigger if you activate an ability of an artifact or creature card not on the battlefield.
2/9/2017 An ability whose cost is simply can be activated as many times as you’d like. Each activation causes Crackdown Construct’s ability to trigger.