msem-instigator

As an additional cost to cast this spell, pay {3} or discard a card.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

When Mukal Reaper enters, you draw a card and you lose 2 life.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Whenever Mukal Sire or another Construct you control enters, Mukal Sire deals 1 damage to each opponent.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

When Mukal Swarmhorde enters, put a +1/+1 counter on each other Construct you control.
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)
Whenever Mukal Warleader attacks, the next Construct spell you cast this turn costs {1} less to cast.

When Mul Daya Elder enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever a land you control enters, put a +1/+1 counter on Mul Daya Elder.

As an additional cost to cast this spell, exile a creature card from your graveyard.
Create a tapped 2/3 black Mummy creature token.

Destroy target creature.

Whenever a creature with flying attacks you, gain control of that creature at end of combat.

Enchant creature
Whenever enchanted creature attacks, it gets +3/+3 and gains trample until end of turn.

Destroy target creature an opponent controls, then that player sacrifices a creature.

({T}: Add {G} or {U}.)
As Mushroom Lagoon enters, you may pay {1}. If you don't, Mushroom Lagoon enters tapped.

Counter target enchantment, instant, or sorcery spell. (Then exile this card. You may cast the creature later from exile.)

{T}: Add {C}.
Whenever Mustering Grounds becomes tapped, if it's enchanted, you may pay {2}. If you do, create a 1/1 white Soldier creature token with vigilance.

Menace
Other attacking Hounds you control get +2/+0.

Whenever Mysteries of Life enters or you create a token, choose one that hasn't been chosen this turn —
• You gain 2 life.
• Draw a card, then discard a card.
• You may tap or untap target permanent.

(As you complete a condition, decode it. After all are decoded, you solve the mystery and transform this.)
When Mystery of the Crashed Craft enters, create two 1/1 red Alien creature tokens with “This creature can't block.”
{MG}—You cast an instant spell.
{MG}—You cast a sorcery spell.

Search your library for up to two cards with different names and reveal them. Target opponent chooses one of those cards. Put the chosen card into your graveyard and the rest into your hand. Then shuffle.

Create a token that's a copy of target creature, except its power and toughness are switched. Sacrifice that token at the beginning of your next end step.

Whenever you cast a spell from exile, you may draw a card.
At the beginning of your upkeep, you may reveal the top card of your library.

When Mystic Seer enters, each player may scry 1.
{2}{U}: Draw a card, then discard a card.

{T}: Add {C}.
{3}, {T}, Sacrifice Mystical Tomb: Return target artifact, enchantment, or legendary card from your graveyard to your hand.

When Mythos Scribe enters, you may return target storied card from your graveyard to your hand. (Enchantments and legendary permanents are storied.)

Stampede — Whenever Nacatl Skirmisher and a creature with greater power attack, creatures you control get +1/+0 until end of turn.
{R}, Sacrifice Nacatl Skirmisher: Destroy target artifact.

{T}, Discard a card: Draw a card.