Hive Mind

Whenever a player casts an instant or sorcery spell, each other player copies that spell. Each of those players may choose new targets for their copy.

Primal Vigor

If one or more tokens would be created, twice that many of those tokens are created instead.
If one or more +1/+1 counters would be put on a creature, twice that many +1/+1 counters are put on that creature instead.

Spectral Searchlight

{T}: Choose a player. That player adds one mana of any color they choose.

Kynaios and Tiro of Meletis

At the beginning of your end step, draw a card. Each player may put a land card from their hand onto the battlefield, then each opponent who didn't draws a card.

Helm of Awakening

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Gate to the Aether

At the beginning of each player's upkeep, that player reveals the top card of their library. If it's an artifact, creature, enchantment, or land card, the player may put it onto the battlefield.

Simic Signet

Gruul Signet

Eye of the Storm

Whenever a player casts an instant or sorcery card, exile it. Then that player copies each instant or sorcery card exiled with Eye of the Storm. For each copy, the player may cast the copy without paying its mana cost.

Sol Ring

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Wild Evocation

At the beginning of each player's upkeep, that player reveals a card at random from their hand. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.

Share the Spoils

When Share the Spoils enters and whenever an opponent loses the game, exile the top card of each player's library.
During each player's turn, that player may play a land or cast a spell from among cards exiled with Share the Spoils, and they may spend mana as though it were mana of any color to cast that spell. When they do, exile the top card of their library.

Noble Benefactor

When Noble Benefactor dies, each player may search their library for a card and put that card into their hand. Then each player who searched their library this way shuffles.