msem-instigator

When Specialized Training Dummy enters, choose a card name.
Other creatures you control with the chosen name get +1/+1.

When Border Seeker dies, search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then you gain 1 life for each land you control.

Menace
When Marrow Raptor enters, you may sacrifice a land or exile a land card from your graveyard. If you do, put a +1/+1 counter on it.

When Lost Empire's Legacy enters, create two Treasure tokens.
{1}, {T}, Sacrifice an artifact: Return target artifact card from your graveyard to your hand.

When Blazeblade Sergeant enters, adjudicate. (Create a white Aura enchantment token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)
Whenever an Aura you control enters, target creature you control gains first strike until end of turn.

Vigilance
Death knell — Tap up to two creatures you don't control. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

When Shapur, the Fifth Shah enters, exile target instant or sorcery card from your graveyard. Until end of turn, you may cast that card. If that spell would be put into a graveyard, exile it instead.
Monument {4}{R} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Frozen Hinterlands enters tapped.
{T}: Add {W} or {U}.
{1}{W}{U}: Until end of turn, Frozen Hinterlands becomes a 4/3 white and blue Spirit creature with with prowess and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

Protector of the Gates can't attack unless it's equipped, enchanted, or has a card inscribed onto it.

{2}{B}, Sacrifice a creature: Draw a card.

Target creature gains indestructible until end of turn. Whenever that creature perseveres this turn, create a 1/1 white Nymph creature token. (A creature perseveres when it survives damage.)

Target creature gets +1/+0 and gains first strike until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Menace
As long as Balefire Harbinger is attacking, creatures in its pack can't be blocked unless defending player pays {1} and 1 life for each creature they control that's blocking one of those creatures. (Two or more creatures you control with equal power are in a pack.)

When Skhorvall Raider enters, if you control an embattled creature, Skhorvall Raider deals 2 damage to any target. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Art of war — At the beginning of your end step, if Raiun Bay Scourge dealt damage to an opponent this turn, gain control of target artifact or enchantment until Raiun Bay Scourge leaves the battlefield.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Menace
{2}{B}: Demigod — Surveil 2. Each opponent loses 2 life and you gain 2 life.
{4}{B}: God — Search your library for two cards with different names and reveal them. An opponent chooses one. Put the chosen card into your graveyard and the rest into your hand. Then shuffle.

Horizon Wayfarer's power and toughness are each equal to the number of differently named lands you control.

Whenever Harvester of Secrets or another creature enters from your graveyard, you may draw a card.
Unearth {2}{U}{B} ({2}{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.)

First strike (This creature deals combat damage before creatures without first strike.)
Whenever a creature you control becomes blocked by a creature, Itava Scourge deals 1 damage to that creature's controller.

When Symbiotic Sprout dies, create two 1/1 green Saproling creature tokens.

Choose one —
• Counter target spell unless its controller pays {2}.
• Draw a card.

Whenever an opponent casts a spell, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Spells your opponents cast cost an additional 2 life to cast until your next turn.

Lionize {G} ({G}, Exile this card from your hand: Put a +1/+1 counter on target creature and it gains the following abilities until end of turn. You may cast this card on a later turn from exile.)
Vigilance, reach

Trample
Cavern Carver has haste as long as you control another creature with flash or haste.

This spell costs {1} less to cast for each Horror you control.
Exile up to one target non-Horror creature.
Coalesce {7}{W} (You may cast this from your graveyard for {7}{W}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)