Roil Eruption

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Roil Eruption deals 3 damage to any target. If this spell was kicked, it deals 5 damage instead.

Island

You Come to a River

Choose one —
• Fight the Current — Return target nonland permanent to its owner's hand.
• Find a Crossing — Target creature gets +1/+0 until end of turn and can't be blocked this turn.

Kaza, Roil Chaser

Flying, haste
{T}: The next instant or sorcery spell you cast this turn costs {X} less to cast, where X is the number of Wizards you control as this ability resolves.

Lightning Strike

Lightning Strike deals 3 damage to any target.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Divination

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

Rift Bolt

Rift Bolt deals 3 damage to any target.
Suspend 1—{R} (Rather than cast this card from your hand, you may pay {R} and exile it with a time counter on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Riddleform

Whenever you cast a noncreature spell, you may have Riddleform become a 3/3 Sphinx creature with flying in addition to its other types until end of turn.
{2}{U}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Rockslide Sorcerer

Whenever you cast an instant, sorcery, or Wizard spell, Rockslide Sorcerer deals 1 damage to any target.

Mountain

Umara Mystic

Flying
Whenever you cast an instant, sorcery, or Wizard spell, Umara Mystic gets +2/+0 until end of turn.