msem-instigator

When you cast an instant or sorcery spell, you may sacrifice Shard Flower. If you do, copy that spell. You may choose new targets for the copy.

Equipped creature gets +1/+1 and has distorted. (It can be blocked by tapped creatures but not untapped creatures.)
Equip {1}

When Shardsong Seedling enters, conjure two cards named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

As Shardstone Rift enters, you may pay 2 life. If you don't, Shardstone Rift enters tapped.
{T}, Sacrifice Shardstone Rift: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

Discard a land card: Draw a card. Shardstorm Elemental gets +1/+0 and gains flying until end of turn. Activate only once each turn.

Return up to two target cards from your graveyard to your hand. Put Shared Reminiscence on the bottom of its owner's library.

{T}: Each player draws a card.

Each creature you control has base power and toughness X/Y, where X is the greatest base power among creatures you control and Y the greatest base toughness among creatures you control.

Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)

Creatures you control get +1/+0.
Ferocious — At the beginning of combat on your turn, creatures you control with power 4 or greater gain trample until end of turn.

Destroy target artifact.

Destroy target noncreature permanent.
Memento {5}{G}{G} (You may cast this from your graveyard for {5}{G}{G}. If you do, put it onto the battlefield transformed after it resolves. Exile it if it would leave the battlefield or not resolve.)

Creatures you control can't be blocked by creatures with power 2 or less.
Whenever you tap a land for mana, add {G}.

Discard a card, then draw a card.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Trample
Improve {1}{R} ({1}{R}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Embattled creatures you control get +2/+0. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you casting a noncreature spell causes an ability of a creature you control to trigger, that creature gains your choice of first strike, haste, menace, or trample until end of turn.

As long as it's your turn, Shell Merc has first strike and prowess.

Prevent all combat damage that would be dealt this turn by each creature without a counter on it.

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.

When Shepherd of Lonely Souls dies, you may return target creature card with mana value 4 or less from your graveyard to your hand.

Shepherd of the People can't be blocked by creatures with power 2 or less.
Whenever another Citizen or Peasant you control enters, Shepherd of the People gets +1/+1 until end of turn.

Whenever Shianne's Guardian or another creature you control enters, you may pay {1}{R}{G}. When you do, that creature deals damage equal to its power to any target.

When Shield of the Unwavering enters, attach it to target creature you control.
Equipped creature gets +2/+2 and has vigilance.
Equip {3}