msem-instigator

Create an X/X Elemental creature token that's all colors.
Reconstruct {X}{G}{G}{G} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

{T}: Add one mana of any color.
{2}, {T}: Choose a color. Add X mana of the chosen color, where X is the number of permanents you control that could produce mana of that color.

Return target creature card from your graveyard to your hand. If you cast Lift Weary Heads from Rest from the graveyard, put it onto the battlefield instead.
Reconstruct {6}{B}{B} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

This spell costs {2} less to cast if it targets a multicolored card.
Return target card from your graveyard to your hand.

Whenever you cast a noncreature spell, you may have target player mill two cards. Then if a player has twenty or fewer cards in their library, put a +1/+1 counter on Living Atrocity.

Once each turn, when a permanent is exiled from the battlefield by a spell or ability you control, you may draw a card.

{T}: Add {C}.
{3}: Living Planet becomes a 2/2 Elemental creature until end of turn. This ability costs {1} less to activate for each creature you control.

{R}{G}, Reveal Living Supernova from your hand: Put a land card from your hand onto the battlefield tapped. Activate only as a sorcery.
Whenever Living Supernova or a land you control enters, exile the top two cards of your library. Until the end of your next turn, you may play those cards.

{T}: Add one mana of any color.
Augmented — As long as you've spent {W}{U}{B}{R}{G} to cast spells this turn, spells you control can't be countered.

When Long Lost Cause enters, each opponent exiles a card from their hand or a creature they control.

When Lost Crew enters or dies, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)

Lost Explorer has first strike as long as it's attacking.
{1}{B}, Exile Lost Explorer from your graveyard: Crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)

When Lust for Life enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Augmented — Whenever a creature you control enters, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, you may sacrifice Lust for Life. If you do, create a token that's a copy of that creature.

When Lysander Jal enters, create a token that's a copy of another target noncreature permanent you control.
Whenever you cast a spell from your graveyard, return target permanent card from your graveyard to your hand.

[+1]: Scry 2. Whenever one or more creatures you control deal combat damage to a player this turn, draw a card.
[–2]: Create a token that's a copy of target creature you control, except the token is 4/4 and has vigilance.
[–7]: You get an emblem with “At the beginning of your draw step, draw two additional cards” and “Creatures you control get +1/+1 for each card you've drawn this turn.”

Enchant creature
When Mantle of the Returned enters, return target creature card from your graveyard to the battlefield. It's a Zombie in addition to its other types.
Enchanted creature gets +1/+1 for each Zombie you control.

Whenever an artifact you control enters, Master of Munitions deals 1 damage to each opponent.

Target creature you control gets +1/+0 until end of turn. It fights up to one target creature you don't control. (Each deals damage equal to its power to the other.)

Meletian Trireme can't be blocked by creatures with power 2 or less.
Whenever Meletian Trireme enters or deals combat damage to a player or planeswalker, scry 1, then draw a card.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

When Meletis Oracle enters, scry 1, then draw a card.

Heroic — Whenever you cast a spell that targets Meletis Stargazer, scry 2.
{T}: Look at the top card of your library. If it's a permanent card with mana value 3 or less, you may reveal it and put it into your hand.

Flash
Flying
When Meletis Stratomancer enters, target creature an opponent controls gets -2/-0 until end of turn.

When Memento Gorgon enters, mill X cards, where X is your devotion to black. Then return a card milled this way to your hand. You lose 1 life. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Whenever Memory of Fatalism dies or you cast a noncreature spell, each opponent loses 2 life and you gain 2 life.
{4}: Put Memory of Fatalism from your graveyard on top of your library.

Counter target spell unless its controller pays {2}. If that spell targets you or a permanent you control, counter that spell instead.