msem-instigator

Creatures you control lose poisonous and can't have or gain poisonous.
Snakes you control deal damage to players in the form of poison counters.

Target player mills seven cards.
Inscribe {3}{U}{B} ({3}{U}{B}: 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.)

Flying
Saki of the Sea and Sky gets +1/+1 for each card inscribed onto it and each permanent attached to it.

Choose a color or card type. Target permanent gains protection from the chosen color or type until end of turn.
Inscribe {3}{W}{U} ({3}{W}{U}: 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.)

Target player sacrifices a creature.
Inscribe {3}{B}{R} ({3}{B}{R}: 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.)

You may have Urushi, the Ripple in the Smoke enter as a copy of any creature on the battlefield, except it's an enchantment. (It's not a creature.)

Vigilance
Art of war — At the beginning of your end step, if Yuso, Light of Jidai dealt damage to an opponent this turn, you may search your library for a creature card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Equipped creature gets +2/+2 and has poisonous 2. (Whenever this creature deals combat damage to a player, that player gets two poison counters.)
Whenever equipped creature attacks, create a 1/1 green Snake creature token with poisonous 1 that's tapped and attacking. Exile that token at end of combat.
Equip {2}

Equipped creature gets +2/+2.
Art of war — At the beginning of your end step, if equipped creature dealt damage to an opponent this turn, untap each equipped creature you control.
Equip {2}

Equipped creature gets +2/+0.
Equip {1}

{T}, Sacrifice a Snake: Choose a counter on target permanent or player. You may put an additional counter of that kind on that permanent or player.

When Eternal Inheritance enters or at the beginning of your upkeep, if you control no Samurai, create a 1/1 colorless Samurai creature token, then you may attach Eternal Inheritance to it.
Equipped creature gets +1/+1.
Equip {1}

Equipped creature gets +3/+2.
Equip {3}

Whenever you cast your first instant or sorcery spell each turn, untap equipped creature.
Equip {1}

Equipped creatures you control get +1/+1.
Equip {2}

When Kiri Yoroi enters, create a 2/2 colorless Spirit creature token and attach Kiri Yoroi to it.
Equipped creatures you control get +1/+1.
Equip {2}

You have hexproof.
Whenever a creature deals combat damage to you or a planeswalker you control, Mask of Shikai deals 1 damage to that creature.

Prevent all combat damage that would be dealt to attacking creatures you control.

Equipped creature gets +1/+0 for each colorless creature you control.
Equip {1}

Equipped creatures you control get +1/+1.
You may activate equip abilities any time you could cast an instant.
Equip {2}

Your opponents play with their hands revealed.

Equipped creature gets +2/+2 and has flying and lifelink.
When equipped creature deals combat damage to a player, unattach Shionoshio, Ocean's Vow, then transform it.
Equip {W}{U}
Shionoshio can be your commander.

Flying, lifelink
Whenever Shioki, Imperial Heir attacks, exile any number of other target nonland permanents you control, then return those cards to the battlefield under their owner's control.

As long as Sigiled Scrollcase is attached to a creature you control, you have no maximum hand size.
Whenever equipped creature dies, draw a card.
Equip {1}

Activated abilities of cards in your hand cost up to {1} less to activate. This effect can't reduce the amount of mana an ability costs to activate to less than one mana.