Trouble in Pairs

If an opponent would begin an extra turn, that player skips that turn instead.
Whenever an opponent attacks you with two or more creatures, draws their second card each turn, or casts their second spell each turn, you draw a card.

Selvala, Heart of the Wilds

Whenever another creature enters, its controller may draw a card if its power is greater than each other creature's power.
{G}, {T}: Add X mana in any combination of colors, where X is the greatest power among creatures you control.

Folio of Fancies

Players have no maximum hand size.
{X}{X}, {T}: Each player draws X cards.
{2}{U}, {T}: Each opponent mills cards equal to the number of cards in their hand.

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Zirda, the Dawnwaker

Companion — Each permanent card in your starting deck has an activated ability. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Abilities you activate that aren't mana abilities cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{1}, {T}: Target creature can't block this turn.

Monologue Tax

Whenever an opponent casts their second spell each turn, you create a Treasure token.

Green Sun's Zenith

Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Smuggler's Share

At the beginning of each end step, draw a card for each opponent who drew two or more cards this turn, then create a Treasure token for each opponent who had two or more lands enter the battlefield under their control this turn.

Kwain, Itinerant Meddler

{T}: Each player may draw a card, then each player who drew a card this way gains 1 life.

Spore Frog

Sacrifice this creature: Prevent all combat damage that would be dealt this turn.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Temple Bell

Biomancer's Familiar

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{T}: The next time target creature adapts this turn, it adapts as though it had no +1/+1 counters on it.

Spellbook

Counterspell

Prevent all combat damage that would be dealt this turn.

Heartstone

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Glasses of Urza

Land Tax

At the beginning of your upkeep, if an opponent controls more lands than you, you may search your library for up to three basic land cards, reveal them, put them into your hand, then shuffle.

Arbor Adherent

{T}: Add one mana of any color.
{T}: Add X mana of any one color, where X is the greatest toughness among other creatures you control.

Anvil of Bogardan

Players have no maximum hand size.
At the beginning of each player's draw step, that player draws an additional card, then discards a card.

Dictate of Kruphix

Flash (You may cast this spell any time you could cast an instant.)
At the beginning of each player's draw step, that player draws an additional card.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Kiora's Follower

Dictate of Karametra

Flash
Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Everybody Lives!

All creatures gain hexproof and indestructible until end of turn. Players gain hexproof until end of turn. Players can't lose life this turn and players can't lose the game or win the game this turn.

Reliquary Tower

Heartbeat of Spring

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Kenrith, the Returned King

{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.