msem-instigator

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}

Exile all nontoken creatures. For each creature exiled this way, return that card to the battlefield under a random player's control.

{T}: Add {C}.
{1}, {T}, Sacrifice Shifting City: Search your library for a basic land or Satrapy card, put it onto the battlefield tapped, then shuffle.

{T}: Add {C}.
{2}, {T}, Sacrifice Shifting Frontiers: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Search your library for a Desert card or a land card with a basic land type and put it onto the battlefield tapped, then shuffle.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Canyon: Choose a basic land type other than Plains. Create a colorless land token that's a Plains and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Cascade: Choose a basic land type other than Island. Create a colorless land token that's an Island and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Crag: Choose a basic land type other than Mountain. Create a colorless land token that's a Mountain and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Grove: Choose a basic land type other than Forest. Create a colorless land token that's a Forest and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Morass: Choose a basic land type other than Swamp. Create a colorless land token that's a Swamp and the chosen basic land type. Activate only during your upkeep.