Spells your opponents cast that target a Merfolk you control costmore to cast.
Abilities your opponents activate that target a Merfolk you control costmore to activate.
9/29/2017 To determine the total cost of an opponent’s spell that targets a Merfolk you control, start with the mana cost or alternative cost that player is paying, add any cost increases, then apply any cost reductions. The converted mana cost of the spell remains unchanged, no matter what the total cost to cast it was.
9/29/2017 Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].”
9/29/2017 Kopala’s abilities won’t affect triggered abilities (starting with “when,” “whenever,” or “at”) that target a Merfolk you control.
9/29/2017 Spells and abilities that target more than one Merfolk you control cost only more to cast or activate.