msem-instigator

Codex — Eleventh Hour Breakthrough; Mentorb; Ostracizer Orb; Possibility Engine; Sealed Riftway; Self Replication. (As this enters, conjure its contents into a shuffled face-up additional library.)
{T}, Sacrifice an artifact: Draw a card from the codex's library.

Lifelink
At the beginning of each end step, if you gained life this turn, you may pay {W/B}. If you do, create a 1/1 white Spirit creature token with flying.

{T}: Add {C}.
{T}: Add {R}, {W}, or {B}. You can't spend this mana to cast a monocolored spell.

Scry X, where X is the number of artifacts you control, then reveal the top card of your library. If it's an artifact card with mana value X or less, put it onto the battlefield. Otherwise, draw a card.

Distribute a vigilance, trample, first strike, and lifelink counter among up to four target creatures you control, then distribute four +1/+1 counters among those creatures.

Flying
Harmony — Until the end of your next turn, you may cast target instant or sorcery card from your graveyard. If that card would be put into your graveyard, exile it instead.
When Aven Acoustimancer enters, harmonize. (Trigger up to one harmony of one permanent you control.)

{T}: Add {W} or {B}.
{W}{B}, {T}: Each opponent loses 1 life and you gain 1 life.

Assault {2}{R}{G} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Shemesh assaults, other creatures you control get +2/+2 and gain trample until end of turn.

({T}: Add {U} or {B}.)
As Ruptured Grotto enters, you may pay {1}. If you don't, Ruptured Grotto enters tapped.

Ammbradu Parasite gets +1/+1 as long as you control a Forest.
{4}{G}: Target creature must be blocked this turn if able.

Counter target spell.

During each of your turns, you may cast a card with a cycling ability from your graveyard by discarding a card in addition to paying its other costs. If that spell would be put into your graveyard, exile it instead.
Cycling {2} ({2}, Discard this card: Draw a card.)

As long as Shambling Morass is on the battlefield or in your graveyard, it's a land in addition to its other types.
When Shambling Morass dies, you may pay {1}. If you do, you draw a card and you lose 1 life.

Mine Delver has first strike as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Each Merfolk and Wizard you control has “Whenever this creature attacks, abound.” (To abound, you may cast a spell that costs less than that creature from your hand without paying its mana cost.)

Reach
Assault {5}{G}{G}{G} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Towering Hydraffe assaults, create a token that's a copy of it.

Search your library for up to two Forest cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
Flashback—Tap three untapped green creatures you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target opponent reveals their hand. You choose a nonland permanent card from it. That player discards that card.

Purge, then you may pay 2 life. If you do, purge again. (To purge, exile two cards that share a type from graveyards. If you do, draw a card.)

When this creature enters, put a -1/-1 counter on a creature you control.
Whenever you put one or more -1/-1 counters on one or more creatures, surveil 2.

Whenever a creature dies, scry 1 and each opponent loses 1 life.

{1}{G}, Discard a card: Target land you control becomes a 3/3 Elemental creature. It's still a land. Exile the top card of your library face down.
Whenever a land creature you control deals combat damage to a player, put a card exiled with Children of Gos into your hand.

Advance {2}{W} (Cast this for {2}{W} to advance it as it enters. {2}{W}: Advance this as a sorcery.)
Whenever Construct Engine advances, create a 1/1 colorless Construct artifact creature token.

When you cast this spell, copy it. You may choose new targets for the copy. (Copies keep functions.)
Draw a card.

When Ragantiar enters, mill five cards.
{3}{B}, Sacrifice a creature: Return target creature card with power X or less from your graveyard to the battlefield, where X is 1 plus the sacrificed creature's power.