An ability whose cost is simply {0} can be activated as many times as you'd like. Each activation causes Crackdown Construct's ability to trigger.
09-02-2017
wotc
Crackdown Construct's ability doesn't trigger if you activate an ability of an artifact or creature card not on the battlefield.
09-02-2017
wotc
An activated mana ability is one that could add mana as it resolves, doesn't have a target, and isn't a loyalty ability.
09-02-2017
wotc
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.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.