"I know these waters better than you know yourselves."

Kopala, Warden of Waves

Spells your opponents cast that target a Merfolk you control cost {2} more to cast.
Abilities your opponents activate that target a Merfolk you control cost {2} more to activate.

The Lost Caverns of Ixalan Commander

Ixalan Promos

Ixalan

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]."

Kopala's abilities won't affect triggered abilities (starting with "when," "whenever," or "at") that target a Merfolk you control.

Spells and abilities that target more than one Merfolk you control cost only {2} more to cast or activate.

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 mana value of the spell remains unchanged, no matter what the total cost to cast it was.