msem-instigator

Whenever a creature you control dies, put a legacy counter on Testament to Heroism.
{T}: Add {C}.
{T}, Remove a legacy counter from Testament to Heroism: Add one mana of any color.

Counter target spell, activated ability, or triggered ability unless its controller pays {X}. (Mana abilities can't be targeted.)

Lifelink
Frenzied Watchkeeper enters with six -1/-1 counters on it.
At the beginning of each end step, if an opponent lost life this turn, remove a -1/-1 counter from Frenzied Watchkeeper.

When Endrison Familiar enters, reveal the top four cards of your library. Put all land cards revealed this way into your hand and the rest into your graveyard.

{W}{B}, Pay X life: Return target creature card with mana value X from your graveyard to the battlefield with a finality counter on it. Activate only as a sorcery and only once each turn.
{W}{B}, Pay 3 life: Return Mehr's Last Captain from your graveyard to the battlefield with a finality counter on it.

Hibernation Den enters tapped.
{T}: Add {W}.
{W}, {T}: You gain 1 life. Activate only as a sorcery and only if you control a white creature.

Whenever a creature you control enters, you may have it deal damage equal to its power to another target creature or planeswalker.
I, II, III — Exile the top two cards of your library. You may put a creature card from among them onto the battlefield with a +1/+1 counter on it. It gains haste.
IV — Creatures you control get +3/+3 and gain trample until end of turn.

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.)
Lifelink

({T}: Add {W} or {B}.)
Gloomcover Steppe enters tapped unless you control a basic Plains or a basic Swamp.

Until end of turn, target creature gets +2/+2, then an additional +2/+2 for each card and token merged with it.

Whenever you draw a card, choose one —
• Dayang's Artistry deals 1 damage to any target.
• You gain 1 life.
• Scry 1.

Whenever you cast a white spell, create a 1/1 white Nymph creature token.

As an additional cost to cast this spell, you may pay {2} and tap an untapped Rogue you control. When you do, copy this spell and you may choose new targets for the copy.
Target creature gets -2/-2 until end of turn.

Haste
Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

Deathtouch
When Pestilent Scavenger enters, you may mill three cards.

Equipped creature gets +1/+0 and can't be blocked.
Equip Actor creature {1}
Equip {3}

Ainok Alpha can't be blocked by more than one creature.
Other Hounds you control get +1/+1 and can't be blocked by more than one creature.

Vigilance
When Expendable Victim dies, create a 1/1 colorless Construct Actor creature token.

Whenever a creature you control deals combat damage to a player, you may draw a card.
Fleeting {1}{U} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

{1}{G}: Marrow Gorger must be blocked this turn if able.

{2}, Exile Cranial Archive: Target player shuffles their graveyard into their library. Draw a card.

When Mystic Mackerel enters, you may have target player mill two cards.
{3}{U}, Sacrifice Mystic Mackerel: Return target enchantment, instant, or sorcery card from your graveyard to your hand.

When Goremound enters, target creature you don't control gets -3/-3 until end of turn. All other creatures you don't control with the same name as that creature get -1/-1 until end of turn.
Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Defender (This creature can't attack.)
Discard a card: Barge Engulfer can attack as though it didn't have defender until end of turn.

Siphon (Each -1/-1 counter you put on your creatures up to their remaining toughness while casting this pays for {1}.)
Gamhaugen Burns deals 3 damage to any target.