msem-instigator

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Worried Vulpine has three or more +1/+1 counters on it, remove them all and transform it.

When this permanent transforms into Worthy Vulpine or at the beginning of combat on your turn, creatures you control gain haste and trample until end of turn.

Target creature you control gets +3/+3 and gains lifelink and trample until end of turn.
Inscribe {3}{G}{W} ({3}{G}{W}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

When Wretched Spawn enters, you may return target permanent to its owner's hand. If you do, that player discards a card.
Unearth {4}{U}{B} ({4}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

Landfall — Whenever a land you control enters, create a 5/5 green Wurm creature token with trample.

Whenever you activate a loyalty ability of Xanigan, the Darkened Cloud, you get an emblem with exalted.
[+2]: Xanigan deals 2 damage to up to one target and you gain 2 life.
[–3]: You draw three cards and you lose 3 life.
[–7]: Xanigan becomes a 7/7 Demon creature with flying and indestructible that's still a planeswalker. Prevent all combat damage that would be dealt to her.

Whenever you cast an instant or sorcery spell, you may have Xenocrata's Fleet become a 4/4 Ship artifact creature with haste until end of turn.
Whenever Xenocrata's Fleet deals combat damage to an opponent, create that many 1/1 red Warrior creature tokens.

(Transcend as a sorcery to gain that type and a +1/+1 counter.)
When Xifang Hu enters, noncreature spells cost {2} more to cast until your next turn.
{1}{W}: Demigod — Whenever a creature attacks this turn, create a 1/1 colorless Spirit creature token.
{4}{W}{W}: God — Distribute a flying, first strike, indestructible, lifelink, vigilance, and +1/+1 counter among any number of creatures you control.

[+2]: Create a 3/3 red Panda creature token.
[–X]: Sacrifice a creature. If you do, search your library for a creature card with mana value less than or equal to X plus the sacrificed creature's mana value. Put that card onto the battlefield, then shuffle.
[–6]: You get an emblem with “Whenever a creature dies, this emblem deals damage equal to that creature's power to any target and you draw that many cards.”

Ferocious — Whenever a creature with power 4 or greater you control enters, untap all lands you control.

You may activate loyalty abilities of Xirix, the Usurper during extra turns any time you could cast an instant.
[+1]: Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
[–2]: Destroy each nonland, non-Xirix permanent with the greatest mana value among non-Xirix permanents on the battlefield.
[–6]: Put target permanent card from a graveyard onto the battlefield under your control.

Whenever you cast a legendary spell, create a 1/1 white Human creature token.
{W}{U}{B}{R}{G}: Search your library for a legendary card, reveal it, put it into your hand, then shuffle. The next legendary spell you cast this turn costs {W}{U}{B}{R}{G} less to cast.

Whenever a nontoken creature you control dies, create a 1/1 black Skeleton creature token.

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Young Tempter enters, you draw a card and you lose 1 life.

Whenever Yri, the Daring Blade and exactly one other creature attack, Yri and that creature can't be blocked by creatures with mana value 3 or less this turn.

Flying
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)
Whenever Zaidha, Seraph of Calamity deals combat damage to a player, choose up to two target nonland permanents that player controls and target nonland permanent you control. Destroy one of those permanents at random.

This spell costs {1} less to cast for each creature that died this turn.
At the beginning of your upkeep, put target creature card from a graveyard onto the battlefield under your control.
{1}, Sacrifice another creature: Zarad, the Final Adversary gains indestructible until end of turn.

{1}{R}, {T}, Sacrifice a land: Create a colorless Desert land token with “{T}: Add {C}.”
{1}{R}, {T}, Sacrifice a Desert: Destroy up to two target lands.

Lifelink
Spells your opponents cast cost an additional {1} to cast for each spell they've cast before it this turn.

Flash
Defender, flying

When Zhedina Envoys leaves the battlefield, create two 1/1 Scout creature tokens that are all colors.

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
{T}: Add {C}.
{1}, {T}: Scry 1.