msem-instigator

Whenever you cast an instant or sorcery spell, create a 1/1 red Alien creature token with “This creature can't block.”
{2}{R}, Sacrifice two Aliens: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature.
Other creatures you control dying causes abilities of that creature to trigger as though it entered.
{2}{B}: Each opponent loses 1 life. You gain life equal to the life lost this way.

Artifacts you control have “{T}: Add one mana of any color.”
{2}{R}{G}: Create a 3/2 green Crocodile creature token with trample. It gains haste until end of turn.

Prowess
Wizardcycling {1}{U} ({1}{U}, Discard this card: Search your library for a Wizard card, reveal it, and put it into your hand, then shuffle.)

Erupting Territory enters tapped.
{T}: Add {B} or {R}.
{1}, {T}: Add one mana of any color.

Vigilance, ward {1}
{T}: Add one mana of any color. If that mana is spent on a creature spell, it enters with an additional +1/+1 counter on it.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Escorted Rider gets +1/+1 as long as you control another creature with flying.

Flying, vigilance
Embattled creatures you control have ward {1}. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)
Whenever one or more creatures you control deal combat damage to a player, put a +1/+1 counter on one of those creatures.

Counter target creature spell.

When Essence of Nurture enters, put a +1/+1 counter on another target creature, then you gain life equal to that creature's toughness.

Create two 1/1 green Frog creature tokens. (Then exile this card. You may cast the creature later from exile.)

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature gets +1/+1 for each enchantment you control and has first strike.

When Ethereal Spellmaster enters, if it was cast, you may search your library for an instant or sorcery card with mana value 3 or less and cast it without paying its mana cost. If you do, shuffle your library. (If it has X in its mana cost, X is 0.)

If you would search your library for one or more cards, you may search for an additional card. (It still follows the same restrictions and effects.)

Flying
Nonartifact permanents entering the battlefield don't cause abilities to trigger.

Embellish {6}{U} (If you cast this spell for {6}{U}, create a 1/1 blue Thopter artifact creature token with flying when it enters.)
Whenever you attack, return any number of nonland permanents with different controllers and mana value less than or equal to the number of artifacts you control to their owners' hands.

Artifact spells you cast cost {1} less to cast.

Whenever Evaldi's Muse or another nontoken creature you control enters, you gain 2 life.
When Evaldi's Muse leaves the battlefield, create two 1/1 green and blue Elf creature tokens.

At the beginning of your upkeep, draw a card and reveal it. You lose life equal to that card's mana value unless you control an Eve planeswalker.

Exile target nonland permanent if its mana value is less than or equal to the greatest number of nonland permanents controlled by a single player.

At the beginning of combat on your turn, if you control a creature with power greater than Ever-Gnawing Rat's, put a +1/+1 counter on Ever-Gnawing Rat.

Trample
Evergrowing Hydra enters with X +1/+1 counters on it.
Whenever another creature you control dies, you may pay {X}, where X is less than or equal to that creature's power. If you do, put X +1/+1 counters on Evergrowing Hydra.

Exile target creature or planeswalker. Its controller conjures a card named Data-Point into their hand. (It's a sorcery that costs {2} with “Draw a card.”)

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Enchant creature
Enchanted creature gets +2/+2.
Whenever enchanted creature attacks, create a 2/2 white Knight creature token that's tapped and attacking.