2022-10-14 : Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities (such as equip and unearth) are activated abilities and will have colons in their reminder text.

2022-10-14 : Myrel, Shield of Argive's first ability prevents opponents from activating abilities of permanents on the battlefield that are artifacts, creatures, and/or enchantments. It doesn't prevent activated abilities from cards in any zone other than the battlefield. Notably, this means that your opponents may still activate abilities of cards in their graveyard (such as unearth).