Busted!

Counter target spell unless its controller pays {X}, where X is the number of words in the name with the most words among permanents you control.

Chance Encounter

Whenever you win a coin flip, put a luck counter on Chance Encounter.
At the beginning of your upkeep, if Chance Encounter has ten or more luck counters on it, you win the game.

Bag Check

Counter target spell, then ask a person outside the game if that spell looks dangerous to them. If they say yes, draw a card, then discard a card.

Entirely Normal Armchair

During your turn, if Entirely Normal Armchair is in your hand, you may hide it on the battlefield.
{0}: Return Entirely Normal Armchair to its owner's hand. Only your opponents may activate this ability and only if they see Entirely Normal Armchair.
{2}, Sacrifice Entirely Normal Armchair: Destroy target attacking creature.

Bitter Reunion

When Bitter Reunion enters the battlefield, you may discard a card. If you do, draw two cards.
{1}, Sacrifice Bitter Reunion: Creatures you control gain haste until end of turn.

Amped Up

This spell costs {1} less to cast for each electrical socket in a wall or floor you can see from your seat.
Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gets +3/+0 and gains haste.

Illicit Auction

Each player may bid life for control of target creature. You start the bidding with a bid of 0. In turn order, each player may top the high bid. The bidding ends if the high bid stands. The high bidder loses life equal to the high bid and gains control of the creature. (This effect lasts indefinitely.)

Winter Sky

Flip a coin. If you win the flip, Winter Sky deals 1 damage to each creature and each player. If you lose the flip, each player draws a card.

Fighting Chance

For each blocking creature, flip a coin. If you win the flip, prevent all combat damage that would be dealt by that creature this turn.

Crazed Firecat

When Crazed Firecat enters the battlefield, flip a coin until you lose a flip. Put a +1/+1 counter on Crazed Firecat for each flip you won.

Befuddle

Target creature gets -4/-0 until end of turn.
Draw a card.

Etali, Primal Storm

Whenever Etali, Primal Storm attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Chaotic Goo

Chaotic Goo enters the battlefield with three +1/+1 counters on it.
At the beginning of your upkeep, you may flip a coin. If you win the flip, put a +1/+1 counter on Chaotic Goo. If you lose the flip, remove a +1/+1 counter from Chaotic Goo.

Artificial Evolution

Change the text of target spell or permanent by replacing all instances of one creature type with another. The new creature type can't be Wall. (This effect lasts indefinitely.)

Skyclaw Thrash

Whenever Skyclaw Thrash attacks, flip a coin. If you win the flip, Skyclaw Thrash gets +1/+1 and gains flying until end of turn.

Guttersnipe

Whenever you cast an instant or sorcery spell, Guttersnipe deals 2 damage to each opponent.

Archaeomancer

When Archaeomancer enters the battlefield, return target instant or sorcery card from your graveyard to your hand.