Pestermite

Flash
Flying
When this creature enters, you may tap or untap target permanent.

Glen Elendra Pranksters

Flying
Whenever you cast a spell during an opponent's turn, you may return target creature you control to its owner's hand.

Nymris, Oona's Trickster

Flash
Flying
Whenever you cast your first spell during each opponent's turn, look at the top two cards of your library. Put one of those cards into your hand and the other into your graveyard.

Vendilion Clique

Flash
Flying
When Vendilion Clique enters, look at target player's hand. You may choose a nonland card from it. If you do, that player reveals the chosen card, puts it on the bottom of their library, then draws a card.

Prickle Faeries

Flying
At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Prickle Faeries deals 2 damage to them.

Invasion of Eldraine

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Eldraine enters, target opponent discards two cards.

Invasion of Eldraine // Prickle Faeries

Brineborn Cutthroat

Flash (You may cast this spell any time you could cast an instant.)
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on this creature.

Slitherwisp

Flash
Whenever you cast another spell that has flash, you draw a card and each opponent loses 1 life.

Sentinels of Glen Elendra

Spellstutter Sprite

Flash
Flying
When this creature enters, counter target spell with mana value X or less, where X is the number of Faeries you control.