msem-instigator

You may exchange a creature you both own and control with a creature card in your hand that has the same mana value.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Creatures you control dying cause abilities of that creature to trigger as though that creature entered.
{2}{W}{B}, Sacrifice another creature: Destroy target nonland permanent.

At the beginning of your upkeep, exile the top card of your library. You may play it this turn. Whenever you cast an instant or sorcery spell exiled this way, you may copy it and you may choose new targets for the copy.

Each player chooses up to one permanent they control of each permanent type, then sacrifices the rest. (The permanent types are artifact, creature, enchantment, land, and planeswalker.)

Flying, vigilance
When Tyriel, Angelic Artisan enters, you may search your library for an Equipment card, reveal it, put it into your hand, then shuffle.
Whenever Tyriel attacks, you may put an Equipment card from your hand onto the battlefield, then attach it to Tyriel.

Tzelin of the Demon Realm can't block.
Whenever a Demon you control enters, you may pay {B}. If you do, return Tzelin from your graveyard to the battlefield with a +1/+1 counter on it.

Target opponent sacrifices half the permanents they control, rounded down.

Concord — As long as there are four or more card types among permanents you control, you may cast the first spell you cast each turn without paying its mana cost.

Create three 1/1 colorless Servo artifact creature tokens.
Exile Unending Armies. At the beginning of your upkeep, if you have more life than each opponent, you may cast it without paying its mana cost. Otherwise, put it into your graveyard.

If you would lose life, exile that many cards from the top of your library instead.
If you would gain life, draw that many cards instead.
When Unhallowed Concordat leaves the battlefield, you lose life equal to the number of cards you own in exile.

Whenever you cast an enchantment spell, reveal the top card of your library. If it's an enchantment card, you may put it onto the battlefield.

If you would draw a card, you may return an instant or sorcery card from your graveyard to your hand instead.
{U}: Draw three cards.

Lifelink
Augmented — Whenever you cast a spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on United Guardian. It loses this ability and gains “Whenever United Guardian attacks, create two 1/1 blue Elemental creature tokens with flying that are tapped and attacking.”

Until end of turn, you can't lose the game, your opponents can't win the game, and your life total can't change.

All creatures have “When this creature enters, destroy target creature with a lesser mana value.”

Exile all lands. For each land card exiled this way, Uttermost Obliteration deals 1 damage to that land's controller.

As Vaertris' Master Plan enters, exile the top five cards of any player's library.
You may play cards exiled with Vaertris' Master Plan.
When there are no cards exiled with Vaertris' Master Plan, return it to its owner's hand.

[+1]: Until end of turn, whenever target creature deals combat damage to a player, that player mills two cards.
[–1]: Tap target creature. It can't become untapped for as long as you control Vaertris, Mindmelder.
[–6]: You get an emblem with “Whenever you draw a card, target player mills three cards” and “{2}{U}: Draw a card.”

Whenever you cast a spell that targets, put a loyalty counter on Valeri Kripac and create a 1/1 white Soldier creature token.
[+1]: Add {R}. If you spend this mana on a spell that targets, that spell can't be countered.
[–2]: Exile target instant or sorcery card from your graveyard. You may play it until the end of your next turn. If you do, exile that spell instead of putting it anywhere else.

Flash
When Veilborn Meddler enters, counter target spell if its mana value is less than or equal to Veilborn Meddler's power.
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on Veilborn Meddler.

[+2]: Destroy up to one target monocolored permanent.
[–3]: Create an 8/8 Elemental creature token with flying, first strike, vigilance, trample, and lifelink that's all colors.
[–5]: Draw three cards. You pay {0} rather than pay the mana cost for the next spell you cast this turn.

As this permanent transforms into Velir, put four loyalty counters on it.
[+1]: Draw two cards, then discard two cards unless you discard a land card.
[–2]: Search your library for a multicolored card, reveal it, put it into your hand, then shuffle.
[–4]: Exile target permanent.

Codex — Heraldry; Whimsy; Villainy; Creativity; Brutality. (As this enters, conjure its contents into a shuffled face-up additional library.)
You may spend mana as though it were mana of any color to cast this codex's contents.
Spells you cast are all colors.

First mate—Your starting deck contains one or more cards of exactly each color and each color pair. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
During each of your turns, you may cast a card of each color from your graveyard. If a spell cast this way would be put into your graveyard, exile it instead.