Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.
15-07-2006
wotc
Can't reduce Snow mana costs.
04-10-2004
wotc
Only affects the generic mana part of activation costs. Colored parts of mana costs are not affected.
04-10-2004
wotc
Can be placed on artifacts with no or zero activation costs, but this has no effect on them. It does not increase the cost to one.
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.