Island

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Stonybrook Schoolmaster

Whenever Stonybrook Schoolmaster becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.

Merrow Commerce

At the beginning of your end step, untap all Merfolk you control.

Sage's Dousing

Counter target spell unless its controller pays {3}. If you control a Wizard, draw a card.

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Plains

Judge of Currents

Whenever a Merfolk you control becomes tapped, you may gain 1 life.

Serum Visions

Merrow Reejerey

Other Merfolk creatures you control get +1/+1.
Whenever you cast a Merfolk spell, you may tap or untap target permanent.