msem-instigator

Death knell — Return an Aura card with mana value 5 or less from your graveyard to the battlefield. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)
As long as Inconspicuous Otter is enchanted or equipped, he's a 3/4 legendary Otter Rogue named Agent O and has menace.

As long as Inconspicuous Platypus is enchanted or equipped, he's a 3/3 legendary Platypus Rogue named Agent P and can't be blocked.

Spells and abilities you control that target Inconspicuous Sheep cost {1} less.
As long as Inconspicuous Sheep is enchanted or equipped, they're a 3/3 legendary Sheep Rogue named Agent S.

As a permanent you control explores an Aura, you may put it onto the battlefield attached to Inconspicuous Stowaway.
As long as Inconspicuous Stowaway is enchanted or equipped, she's a legendary 2/3 Cat Rogue named Agent C and has double strike.

Create a tapped colorless Powercell artifact token with “{T}: Add {C}.” It doesn't untap during its controller's next untap step.

Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Whenever Indebted Burglar becomes blocked, defending player loses 1 life.

{T}: Add {C}.
{5}, {T}: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

Sacrifice Indomitable Bear: Creatures you control gain indestructible until end of turn.

When Indomitable Duo enters, choose up to two creature card names.
Whenever Indomitable Duo attacks, put a +1/+1 counter on each creature you control with a name chosen by Indomitable Duo.

Enchant creature
Enchanted creature gets +3/+2 and attacks each combat if able.

Target creature you control deals damage equal to its power to target creature you don't control.
Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

{T}, Pay 1 life: Add {B} or {R}.
{2}, {T}, Sacrifice Industrial District and another permanent: Draw a card. Activate only during your turn.

Create three 1/1 red Human creature tokens with haste. Sacrifice those tokens at the beginning of the next end step.
Draw a card.

Flash
Enchant creature
When Ineffable Patronage enters, it deals 4 damage to up to one target attacking or blocking creature.
Enchanted creature gets +2/+2.

This spell can't be countered.
Inescapable Blaze deals 6 damage to any target.

Target creature gets -1/-1 until end of turn.
Threshold — You may destroy that creature instead if seven or more cards are in your graveyard.

{W}{B}, Shuffle Inexorable Explorer into your library: Return target creature card from your graveyard to the battlefield.
{W}{B}, Sacrifice a creature: Return Inexorable Explorer from your graveyard to the battlefield tapped.

When Inexperienced Martyr dies, each opponent loses 1 life.

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature gets -1/-1.
Whenever enchanted creature attacks, its controller loses 2 life.

Deathtouch
Whenever Infected Null attacks, each player loses 1 life.

When Infectious Corpse dies, each player loses 2 life.

Whenever Infernal Barrier is dealt damage, it deals 1 damage to each opponent.

Infernal Flames deals 3 damage to target player or planeswalker.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

Enchant creature
Enchanted creature gets +3/+0 and has trample.
Madness {1}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)