msem-instigator

Whenever Wavering Sorcerer attacks, you may switch its power and toughness until end of turn.
Unveil {3}{U}{R} ({3}{U}{R}: Transform this. Unveil only as a sorcery.)

{1}{W}, {T}, Sacrifice Prophet of Pacifism: Prevent all damage that would be dealt to players this turn.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Flash
Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)

Flash
Flying
{U}, Sacrifice this creature: Counter target noncreature spell unless its controller pays {2}.

Equipped creature gets +2/+1 and has flying.
Equip {3}

Enchant creature
When Double Arming enters, put a +1/+1 counter on enchanted creature.
Enchanted creature has menace.
{5}: Return Double Arming to its owner's hand.

Once each turn, if a triggered ability of another legendary permanent you control would trigger, you may have it trigger an additional time.

Thriving Heath enters tapped.
As Thriving Heath enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Each opponent sacrifices a creature. Whenever one or more players lose life this turn, repeat that process.

Haste
Whenever Desperate Reconnoiterer becomes untapped, scry 1.

Flying

Return target creature card with mana value 3 or less from your graveyard to the battlefield.
Fabled {4}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

Create a 1/1 colorless Human creature token. Put your choice of a flying, vigilance, prowess, or hexproof counter on it. If you control a permanent with mana value 5 or greater, instead put any number of those counters and a +1/+1 counter on it.

{1}{W}, Sacrifice Town Elder: Return target artifact or enchantment card from your graveyard to your hand.

I, II — Each opponent loses 2 life and you gain 2 life.
Discovery — At the beginning of your end step, you draw a card and you lose 2 life.

Counter target spell unless its controller pays {2}. If there are three or more counters among permanents you control, counter that spell instead.

When Adept of Rations enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Tokens you control have “{2}, {T}, Sacrifice this token: You gain 3 life.”

Whenever Pineblight Caribou enters or attacks, you may have it consume a land. If you do, draw a card and you gain 2 life. (To consume a land, sacrifice a land or exile a land card from your graveyard.)

This spell costs {1} less to cast for each creature you control that's in a pack. (Two or more creatures you control with equal power are in a pack.)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
If you're in a renaissance, you may have up to one target creature or planeswalker gain indestructible until end of turn.
Destroy all creatures and planeswalkers.

When Imperfect Stone enters, mill three cards.
{T}: Add one mana of any color.

Search your library for a basic land card and put it onto the battlefield tapped, then shuffle. You gain 1 life for each land you control.

Trample
Other Dwarves and Elves you control get +1/+1.
If Harl and Finn or another Dwarf or Elf you control entering the battlefield or attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Menace
Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each creature card in your graveyard.

{T}: Add {C}.
{5}, {T}, Sacrifice Ascendant's Cell: You may activate loyalty abilities of planeswalkers you control twice this turn rather than only once.