Fluxcharger

Flying
Whenever you cast an instant or sorcery spell, you may switch Fluxcharger's power and toughness until end of turn.

Phase Dolphin

Whenever Phase Dolphin attacks, another target attacking creature can't be blocked this turn.

Mannichi, the Fevered Dream

{1}{R}: Switch each creature's power and toughness until end of turn.

Crag Puca

{U/R}: Switch Crag Puca's power and toughness until end of turn.

Prophetic Flamespeaker

Double strike, trample
Whenever Prophetic Flamespeaker deals combat damage to a player, exile the top card of your library. You may play it this turn.

Valakut Fireboar

Whenever Valakut Fireboar attacks, switch its power and toughness until end of turn.

Twisted Image

Switch target creature's power and toughness until end of turn.
Draw a card.

Charix, the Raging Isle

Spells your opponents cast that target Charix, the Raging Isle cost {2} more to cast.
{3}: Charix gets +X/-X until end of turn, where X is the number of Islands you control.

Dwarven Thaumaturgist

{T}: Switch target creature's power and toughness until end of turn.

Wildfire Eternal

Afflict 4 (Whenever this creature becomes blocked, defending player loses 4 life.)
Whenever Wildfire Eternal attacks and isn't blocked, you may cast an instant or sorcery spell from your hand without paying its mana cost.

Master of Winds

Flying
When Master of Winds enters, draw two cards, then discard a card.
Whenever you cast an instant, sorcery, or Wizard spell, you may have Master of Winds's base power and toughness become 4/1 or 1/4 until end of turn.

Merfolk Thaumaturgist

Mistford River Turtle

Whenever Mistford River Turtle attacks, another target attacking non-Human creature can't be blocked this turn.

Inside Out

Benthic Infiltrator

Devoid (This card has no color.)
Ingest (Whenever this creature deals combat damage to a player, that player exiles the top card of their library.)
Benthic Infiltrator can't be blocked.

Invent

Search your library for an instant card and/or a sorcery card, reveal them, put them into your hand, then shuffle.

Invert

Switch the power and toughness of each of up to two target creatures until end of turn.

Invert // Invent

Crookclaw Transmuter

Flash
Flying
When Crookclaw Transmuter enters, switch target creature's power and toughness until end of turn.

Serendib Sorcerer

{T}: Target creature other than Serendib Sorcerer has base power and toughness 0/2 until end of turn.