msem-instigator

As long as you control another white creature, Mavisa's Familar has lifelink. The same is true for blue and flying, black and deathtouch, and red and trample.

[+1]: Untap up to two target creatures and/or lands.
[–2]: Choose a color. Draw cards equal to the number of creatures you control of the chosen color.
[–7]: Reveal the top ten cards of your library. Put all creature and land cards revealed this way onto the battlefield and the rest into your hand.

Reach
When Mawdryk's Harrier enters, look at the top six cards of your library. You may put an Elf card with lesser mana value from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Other Elves you control get +1/+1.

Landfall — Whenever a land you control enters, add {G}.
{3}{G}: Target creature you control gets +2/+2 until end of turn.

When you cast this spell from anywhere other than your hand, it deals 5 damage to any target.
Trample

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)

When Meadow Songstress enters, conjure three cards named Meadow Songstress and shuffle them into your main library.
Whenever a nontoken creature you control enters, if it shares a name with one or more other creatures you control, draw a card.

Enchant creature you control
Whenever enchanted creature attacks, mill three cards.
When enchanted creature leaves the battlefield, create an X/X green Spirit creature token, where X is equal to the number of card types among cards in your graveyard.

Meandering Path enters tapped unless you control one or fewer other lands.
{T}: Add {R} or {G}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Indestructible (Damage and effects that say “destroy” don't destroy this creature.)

When Mechanical Mastodon enters, you may return another target permanent you control to its owner's hand.

Deploy 4 (As this enters, you may tap any number of other creatures you control with total power 4 or more.)
When Mechanical Tactician enters deployed, tap up to two target creatures an opponent controls. Those creatures don't untap during their controller's next untap step.

Mechanized Ideal gets +X/+Y, where X is the highest base power among other creatures you control and Y is the highest base toughness among other creatures you control.

Artifact vision (Whenever this or another artifact you control enters, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Mechanomind Researcher envisions an artifact card, put a +1/+1 counter on it.

When Medical Mask enters, prevent the next 3 damage that would be dealt to any target this turn.
{4}, Sacrifice Medical Mask: Prevent the next 6 damage that would be dealt to any target this turn.

Equipped creature gets +1/+1.
Whenever equipped creature becomes the target of a spell, you gain 3 life.
Equip {4}

Trample
Enchantment spells and Aurashaper spells you cast cost {1} less to cast.
Whenever another enchantment you control enters, draw a card.

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.)

Destroy target artifact.
Catalyze. (The next spell you cast this turn costs {1} less to cast.)

Enchant creature
When Melt the Chains enters, exile the top two cards of your library. Until the end of your next turn, you may play those cards.
Enchanted creature gets +3/+0.

Melt the Earth deals 2 damage to each creature.

Melting Point deals 2 damage to any target.

Memorial Ground enters tapped.
{T}: Add {C}.
{4}, {T}, Sacrifice Memorial Ground: Return target card from your graveyard to your hand.

Rapport — Whenever Memorial of Forgotten Heroes and at least one other creature you control become tapped, put a +1/+1 counter on one of those creatures.
{T}, Tap an untapped creature you control: Add one mana of any color.

{T}: Add {C}.
{T}, Exile Memorial of the Fallen: Shuffle your graveyard into your library.